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Stephen  h JLWE3  w 

CC©LLEC-nON. 


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P 


EXPERIMENTAL  INQUIRY 

INTO 

THE  LAWS 

OF  THE 

VITAL  FUNCTIONS, 

WITH 

SOME  OBSERVATIONS  ON  THE  NATURE  AND  TREATMENT 


OF 

INTERNAL  DISEASES; 

BY 

A.  P.  WILSON  PHILIP,  M.D.  F.R.S.E. 

Fello-w  of  the  College  of  Physicians  of  Edinburgh,  Lie. 

IN  par  t r e-p  ublished, 

BY  PERMISSION  of  the  PRESIDENT  of  the  ROYAL  SOCIETY, 

FROM  THE 

PHILOSOPHICAL  TRANSACTIONS  OF  1815  & 1817, 

WITH 


THE  REPORT  OF  THE  NATIONAL  INSTITUTE  OF  FRANCE 
ON  THE  EXPERIMENTS  OF  M.  LE  GALL  01 S, 

AND 

OBSERVATIONS  ON  THAT  REPORT 

PHILADELPHIA: 

PUBLISHED  BY  EDWARD  & RICHARD  PARKER, 


NO.  178,  MARKET  STREET. 

J.  R.  A.  SKERRETT,  PRINTER. 


1818 


Digitized  by  the  Internet  Archive 
in  2016 


https://archive.org/details/experimentalinqu01phil 


CONTENTS. 


Preface  .... 
An  Experimental  Inquiry,  £fc. 


Page  vii 


PART  I. 


Of  the  state  of  our  knowledge  respecting  the 
principle  on  which  the  action  of  the  heart 
and  blood  vessels  depends,  and  the  relation 
which  subsists  between  them  and  the  nerv- 


Tlie  Report  made  to  the  Class  of  Physical 
and  Mathematical  Sciences  of  the  Imperial 
Institute  of  France  on  the  work  of  M.  le 
Gallois,  entitled,  Experiences  sur  le  Prin- 
cipe de  la  vie,  notamment  sur  celui  des 
mouvemens  du  coeur,  et  sur  le  siege  de  ce 
principe  ......  2 


Observations  on  the  foregoing  Report  . 5t 


ous  system 


1 


CHAP.  I. 


CHAP.  II. 


IV 


PAET  II. 

Experiments  made  with  a view  to  ascertain 
the  laws  of  the  vital  functions  . . 64 

CHAP.  I. 

On  the  principle  on  which  the  action  of  the 
heart  and  vessels  of  circulation  depends  66 

CHAP.  n. 

On  the  relation  which  subsists  between  the 
heart  and  vessels  of  circulation , and  the 
nervous  system  .•  . . 76 

CHAP.  HI. 

On  the  principle  on  which  the  action  of  the 
muscles  of  voluntary  motion  depends , and 
the  relation  which  they  bear  to  the  nervous 
system  ......  94 

CHAP.  IV. 

On  the  comparative  effects  of  stimuli  appli- 
ed to  the  brain  and  spinal  marrow  on  the 
heart  and  muscles  of  voluntary  motion  100 

CHAP.  V. 

On  the  principle  on  which  the  action  of  the 
vessels  of  secretion  depends,  and  the  re- 
lation which  they  bear  to  the  nervous  sys- 
tem ......  113 

SECT.  I. 

On  the  effect  of  withdrawing  the  nervous 
influence  from  secreting  surfaces  . 114 


V 


SECT.  II. 

On  the  nature  of  the  nervous  influence  119 

SECT.  III. 

Inferences  from  the  preceding  Sections  134 

CHAP.  VI. 

On  the  principle  on  which  the  action  of  the 
alimentary  canal  depends  ; with  some  ob- 
servations on  an  opinion  of  J\lr.  Hunter.  138 

CHAP.  YII. 

On  the  relation  which  the  alimentary  canal 


bears  to  the  nervous  system 

147 

SECT.  I. 

On  the  process  of  Digestion. 

149 

SECT.  II. 

On  the  effects  on  the  stomach  and  lungs  of 
destroying  certain  portions  of  the  spinal 
marrow,  compared  with  those  of  dividing 
one  or  both  of  the  eighth  pair  of  nerves  163 

CHAP.  VIII. 

On  the  cause  of  minimal  Temperature  . 175 

CHAP.  IX. 

On  the  use  of  the  Ganglions  . . 185 

CHAP.  X. 

On  the  relation  ichich  the  different  functions 
of  the  animal  body  bear  to  each  other,  and 
the  order  in  which  they  cease  in  dying  200 
2 


VI 


CHAP.  XI. 

A review  of  the  inferences  from  the  preced- 
ing experiments  and  observations  . 234 

CHAP.  XH. 

On  the  application  of  the  foregoing  experi- 
ments and  observations  to  explain  the  na- 
ture and  improve  the  treatment  of  diseases  249 
Of  Sanguineous  Apoplexy  . . . 252 

Of  Inflammation  ....  258 

Of  Nervous  Apoplexy  ....  288 

Of  Affections  of  the  Spinal  Marrow  . 299 

Of  Asthma  and  Dyspepsia  . . . 303 

Of  Suspended  Animation  . . . 328 

Of  Sympathy  .....  330 

Appendix  ......  333 


PREFACE. 


THE  obscurity  of  the  nature  of  Internal  Dis- 
eases, of  which  physicians  have  always  complain- 
ed, seems  to  arise  from  sweral  causes;  the  diffi- 
culty in  those  diseases  of  referring  the  painful 
feeling  to  the  seat  of  the  injury,  proceeding  from 
the  indistinctness  with  which  we  refer  to  internal 
parts,  and  other  parts  sympathising  with  the  part 
affected  ; the  deficiency  of  our  knowledge  of  mor- 
bid anatomy,  in  consequence  of  which  we  are  not 
always  enabled  from  the  train  of  symptoms  to 
infer  the  derangement  of  structure  ; our  ignorance 
of  the  function  of  many  internal  parts,  and  where 
we  have  a knowledge  of  the  function,  our  igno- 
rance of  the  principle  on  which  it  depends.  If 
such  he  the  causes  of  the  obscurity  of  the  nature 
of  Internal  Diseases,  we  may  easily  perceive  the 
objects  which  ought  to  be  kept  in  view  in  our  en- 
deavours to  obtain  a more  correct  knowledge  of 
them,  and  consequently  of  the  means  of  cure 
adapted  to  them. 

By  the  frequent  inspection  of  dead  bodies,  we 
learn  to  connect  particular  trains  of  symptoms 
with  the  changes  of  structure  which  occasion  them, 
for  although  the  sensations  of  which  the  patient 
complains  are  often  ill  defined,  and  sometimes  not 


Vlll 


referred  to  the  seat  of  the  morbid  action,  yet  the 
same  morbid  action  almost  always  produces  nearly 
the  same  train  of  symptoms.  Nothing  appears 
more  to  have  retarded  the  progress  of  medical 
knowledge,  than  the  obstacles  which  have  in  all 
ages  been  opposed  to  the  inspection  of  dead  bo- 
dies. The  great  importance  of  the  information 
thus  obtained,  however,  has  been  slowly  recon- 
ciling the  public  mind  to  it ; and  we  may  with 
confidence  anticipate  the  greatest  improvements 
from  the  increasing  frequency  of  this  practice ; 
without  which  we  can  no  more  acquire  a know- 
ledge of  the  diseased  states  of  the  body,  than  we 
can  of  its  healthy  state  without  the  aid  of  anatomy. 

But  neither  anatomy  nor  the  inspection  of  mor- 
bid bodies  can  teach  us  the  nature  of  the  functions. 
A knowledge  of  them  can,  only  be  acquired  by 
comparing  the  structure  of  the  organs  with  the 
actions  observed  in  them  while  their  vital  power 
remains.  Some  of  these  actions  are  the  objects  of 
simple  observation  in  our  own  bodies  and  those 
of  other  animals.  Anatomy,  for  example,  teaches 
us  the  structure,  position,  and  attachments  of  the 
muscles;  observation  readily  points  out  their  func- 
tion, and  by  the  lesion  of  this  function  we  judge 
of  the  extent  and  degree  of  their  morbid  affec- 
tions, and  are  consequently  guided  in  the  appli- 
cation of  our  remedies.  But  there  are  other  and 
more  important  functions,  which  in  the  entire  ani- 
mal are  hidden  from  our  view.  To  ascertain 


IX 


their  nature,  experiments  must  be  made  on  the  liv- 
ing and  newly-dead  animal.  We  shall  find  tiiat 
many  parts  retain  their  vital  actions  for  a certain 
time  after  what  we  call  death. 

To  the  aversion  to  experiments  on  living  ani- 
mals, which  every  man  must  feel,  we  may,  I 
think,  in  a great  measure,  ascribe  the  little  pro- 
gress which  has  been  made  in  this  essential 
branch  of  medicine.  Something  too  must  be  as- 
cribed to  the  obscurity  of  the  subject.  The  inter- 
nal functions  of  animals  are  of  a nature  so  differ- 
ent from  any  thing  which  we  are  accustomed  to 
see  around  us,  that  our  previous  experience  gives 
us  little  assistance  in  attempting  to  trace  their 
laws,  and  our  progress  is  necessarily  slow  and 
difficult.  Hence  it  appears  to  have  been  that  the 
earlier  Physiologists,  disgusted  with  the  task 
placed  before  them,  evaded  it;  and  endeavoured 
by  ingenious  fictions  to  deceive  their  readers.  It 
is  now  universally  agreed  tiiat  if  any  progress  can 
be  made  in  Physiology,  it  is  not  by  the  wander- 
ings of  fancy,  but  by  patience  and  by  labour. 
We  are  amused  with  the  reveries  of  Stahl,  but  for 
instruction  we  look  to  the  experiments  of  Haller. 
And  to  similar  experiments  we  must  look  for  all 
the  information  we  can  obtain  on  this  subject. 
The  hope  of  adding  something  to  our  knowledge 
of  the  vital  functions,  and  thus  improving  the 
treatment  of  their  diseases,  induced  the  author  to 
undertake  the  following  Inquiry. 


X 


From  the  foregoing  view  of  the  subject  it  will 
be  admitted,  I think,  that  few  writers  have  stronger 
claims  on  the  indulgence  of  the  public  than  the 
Physiologist,  provided  his  endeavours  are  ration- 
ally directed.  The  knowledge,  which  it  is  his 
aim  to  acquire  and  communicate,  is  of  the  most 
important  kind,  while  his  means  of  information 
are  always  laborious,  and  often  of  a painful  na- 
ture. These  claims  are  increased  by  the  circum- 
stances in  which  he  is  usually  placed.  No  per- 
son is  fitted  for  physiological  inquiries  who  has 
not  obtained  a competent  knowledge  of  the  differ- 
ent -branches  of  Medicine.  This  knowledge  is 
acquired  with  so  much  difficulty,  and  depends  so 
much  on  actual  observation,  that  few  who  do  not 
practice  medicine  as  a profession  ever  acquire  it. 
The  Physiologist,  therefore,  generally  pursues  his 
inquiries  amidst  anxious  and  fatiguing  engage- 
ments of  a different  kind,  and  of  such  a nature 
that  all  others  must  give  place  to  them.  I do 
not  mention  these  circumstances  as  affording  any 
apology  for  inaccuracy  in  points  of  consequence, 
because  the  writer  owes  it  to  the  public  to  with- 
hold his  communications  till  he  thinks  himself  as- 
sured of  their  accuracy ; but  they  may,  I hope, 
be  admitted  as  an  apology  for  less  important  er- 
rors. The  errors  of  the  following  Inquiry  are  not 
those  of  precipitation.  It  is  above  fifteen  years 
since  some  of  the  experiments  which  I am  about 
to  relate,  and  many  connected  with  them,  were 


XI 


made.  None  have  been  made  within  the  last 
year,  during  which  I have  employed  the  time  I 
could  allot  to  such  engagements  in  arranging  my 
experiments,  comparing  them  together,  and  en- 
deavouring to  guard  against  hasty  inferences, 
which  it  is  difficult  to  do  at  the  time  the  experi- 
ments are  made. 

I have  endeavoured  as  much  as  possible  to 
avoid  experiments  on  living  animals.  Most  of 
those  related  in  the  following  Inquiry  were  made 
on  the  newly-dead  animal ; and  it  will  appear,  I 
think,  from  what  I am  about  to  lay  before  the 
reader,  that  for  many  experiments,  for  which  the 
living  animal  has  been  thought  necessary,  the 
newly-dead  animal  may  be  used  w ith  equal,  and 
sometimes  with  greater  advantage.  When  it  was 
necessary  to  experiment  on  the  living  animal,  I 
uniformly  observed  the  following  rules;  to  de- 
stroy the  sensibility  previous  to  the  experiment, 
w hen  this  could  be  done  without  influencing  the 
result ; when  several  animals  were  equally  fit  for 
the  experiment,  to  choose  the  one  which  would 
suffer  least  from  it ; when  there  w ere  several  w ays 
of  performing  the  experiment,  to  choose  the  way 
which  would  occasion  least  suffering;' if  the  ex- 
periment was  necessarily  fatal,  to  destroy  the 
animal  as  soon  as  the  purpose  in  view  was  an- 
swered ; and  to  take  such  precautions  as  rendered 
as  few  repetitions  as  possible  requisite. 


XU 


I have  been  much  indebted  in  making  the  ex- 
periments to  the  kind  assistance  of  several  gen- 
tlemen; particularly  Mr.  Hastings,  late  House 
Surgeon  to  the  Worcester  Infirmary,  Mr.  Shep- 
pard, Surgeon  in  Worcester,  and  Mr.  Herbert 
Cole,  successor  to  Mr.  Hastings.  I shall  fre- 
quently have  occasion  to  mention  those  gentlemen. 


j 


AN 


EXPERIMENTAL  INQUIRY, 

#c. 

THE  following  Treatise  is  divided  into  two 
Parts.  In  the  first  Part  I shall  make  the  reader 
acquainted  with  the  state  of  our  knowledge 
respecting  the  principle  on  which  the  action  of 
the  heart  and  blood  vessels  depends,  and  the 
relation  which  subsists  between  them  and  the 
nervous  system,  at  the  time  my  experiments 
were  begun ; as  on  this,  all  our  knowledge  of 
the  vital  functions  more  or  less  immediately  de- 
pends. In  the  second,  I shall  relate  these  ex- 
periments, and  point  out  the  inferences  to  which 
they  seem  to  lead. 

PART  I. 

Of  the  state  of  our  knowledge  respecting  the 
principle  on  which  the  action  of  the  heart  and 
blood  vessels  depends , and  the  relation  which 
subsists  between  them  and  the  nervous  system . 

The  object  of  this  Part  cannot  I think  be 
better  accomplished  than  by  laying  before  the, 

3 


2 


reader  a translation  of  the  Report  of  the  Com- 
mittee of  the  National  Institute  of  France,  on 
the  Experiments  of  M.  le  Gallois,  and  such  ob- 
servations on  it  as  it  appears  to  demand. 


CHAP.  I. 

• 

The  Report  made  to  the  Class  of  Physical  and 
Mathematical  Sciences  of  the  Imperial  Insti- 
tute of  France  on  the  work  of  M.  le  Gallois , 
entitled  Experiences  sur  le  Principe  de  la  vie, 
notamment  sur  celui  des  mouvemens  du  coeur 
et  sur  le  siege  de  ce  Principe. 

The  Class  having  charged  M.  de  Humboldt, 
M.  Halle  and  me,*  to  make  a report  to  it  on 
the  Memoir  read  at  a meeting  of  the  3d  of 
June  last,  by  M.  le  Gallois,  Doctor  of  Medicine, 
respecting  the  nature  of  the  power  of  the  heart, 
and  whence  it  derives  its  power, f we  are  about 
to  present  to  it  a detail  which  will,  perhaps, 
be  as  long  as  the  Memoir  itself,  because  with- 
out the  necessary  details  and  explanations  it 

*M.  Percy. 

t “ Concernant  le  principe  des  forces  ducceur,  et  le  siege 
de  ce  principe.” 


3 


would  be  impossible  to  appreciate  all  the  merit 
of  this  excellent  work. 

It  was  not  till  after  the  circulation  of  the 
blood  was  discovered  by  Harvey,  early  in  the 
seventeenth  century,  that  Physiologists  turned 
their  attention  to  the  cause  and  mechanism  of 
the  movements  of  the  heart,  which  have,  since 
that  time,  given  rise  to  so  many  different  sys- 
tems. 

We  shall  not  speak  of  those  of  Descartes,*  of 
Sylvius  de  le  Boe,f  of  Borelli.J  They  are  very 
absurd,  and  serve  only  to  prove  how  unfortu- 
nate were  the  first  attempts  to  explain  one  of 
the  most  important  functions  of  the  animal 
ceconomy.  We  shall  begin  with  the  distinction 
which  Willis  first  pointed  out  between  the 
nerves  destined  for  the  voluntary,  and  those 
for  the  involuntary  motions.  He  placed  the 
origin  of  the  latter  in  the  cerebellum,  of  the 
former  in  the  brain,  properly  so  called.  He 
taught  that  the  motions  of  the  heart,  and  other 
vital  organs,  experience  no  interruption,  be- 
cause the  cerebellum  is  in  a state  of  constant 

* L’homme  de  Rene  Descartes,  et  la  formation  du  foetus 
avec  les  remarques  de  Louis  Laforgue,  Paris,  1677,  p.  4 and 
106. 

t Francisci  De  la  Boe  Sylvii  Opera  Medica  Genevee,  1681, 
p.  5,  27,  28,  33,  475. 

t Joh.  Alph.  Borelli  de  motu  animalium.  Hagse  Comitum, 
1743,  p.  89—92. 


activity ; but  that  the  organs  of  voluntary  mo- 
tion, on  the  contrary,  require  repose,  because 
the  brain  acts  only  by  intervals.*  This  dis- 
tinction of  Willis  was  very  generally  admitted 
till  the  middle  of  the  last  century.  It  was 
chiefly  with  a view  to  it  that  the  division  of  the 
eighth  pair  of  nerves,  from  which  it  was  main- 
tained that  almost  all  the  nerves  of  the  heart 
proceed,  was  performed  in  different  countries. 
The  object  was  to  prove  that  it  is  from  the 
cerebellum  that  the  heart  derives  all  its  power, 
and  it  was  alledged  that  the  animal  died  in  this 
experiment,  in  consequence  of  the  communica- 
tion between  these  organs  being  interrupted. — 
But,  besides  that  it  dies  too  slowly  to  permit 
us  to  ascribe  its  death  to  this  cause,  it  has  been 
proved  in  later  times  by  several  Philosophers, 
and  particularly  by  M.  le  Gallois,  in  a memoir 
which  the  Class  ordered  to  be  inserted  in  the 
transactions  of  learned  correspondents,  that 
death  here  proceeds  from  quite  a different 
cause.  It  has  sometimes  happened,  indeed, 
that  animals  have  died  almost  suddenly  after 
the  division  of  the  nerves  in  question,  and  the 
partizans  of  Willis  have  not  failed  to  lay  much 
stress  on  this  circumstance,  of  which  their  ad- 
versaries could  give  no  satisfactory  explanation. 

* Tho.  Willis  opera  omnia,  edente  Ger.  Balsio  Amstelo- 
dami,  1682,  Tom.  1,  de  cerebri  anatome,  cap.  xv.  p.  50. 


5 


But  M.  le  Gallois  has  demonstrated  in  the  me- 
moir to  which  we  have  just  alluded,  that  sudden 
death  in  this  case  only  happens  in  certain  kinds 
of  animals,  and  in  these  only  when  they  are 
very  young,  and  that  it  is  the  effect  of  suffoca- 
tion,* more  or  less  complete  from  the  shutting  of 
the  glottis.  There  is  nothing  then  in  these  facts 
in  favour  of  Willis,  to  which  we  may  add,  that 
the  eighth  pair  of  nerves  does  not  arise  from  the* 
cerebellum,  and  that  most  of  the  nerves  of  the 
heart  do  not  belong  to  this  pair. 

Boerhaave  was  of  the  same  opinion  with 
Willis,  but  besides  the  nervous  influence,  he 
admitted  two  other  causes  of  the  motions  of 
the  heart;  the  action  of  the  blood  of  the  coro- 
nary arteries  on  its  fibres,  and  of  the  venous 
blood  on  the  surface  of  its  cavities.  Accord- 
ing to  him  the  concurrence  of  these  three 
causes  produces  the  systole,  and  the  simultane- 
ous interruption  of  their  action  in  consequence 
of  the  systole  gives  rise  to  the  diastole,  during 
which  their  action  is  renewed,  f But  this  ex- 
planation, with  the  exception  of  what  regards 
the  stimulus  of  the  blood  on  the  internal  sur- 
face of  the  heart,  is  contradicted  by  fact,  which 

* Asphixie.  This  I translate  suffocation,  because  we  use 
the  term  Asphixia  in  a very  different  sense.  Culleni  Synop- 
sis Nos.  Method.  Gen.  44. 

t Her.  Boerhaave  Instit.  Medicse,  § 409. — Vanswieten  in 
Aphorismos,  &c.  Lugduni  Batav.  1745,  Tom.  2,  p.  18, 


6 


lias  not  prevented  its  reception  in  the  schools, 
with  another  error  that  has  made  no  less  noise. 

We  allude  to  Stahl,  and  his  soul  or  Archaeus, 
which,  regulating  all  the  movements  of  the 
living  body,  subjecting  them  to  the  will,  or 
rendering  them  independent  of  it,  according 
as  they  are  merely  useful,  or  absolutely  neces- 
sary to  life,  presides  above  all  over  those  of  the 
heart,  and,  through  the  influence  of  the  nerves, 
insures  their  continuance;  a species  of  reverie 
which  is  inconsistent  with  all  the  true  principles 
of  Physiology. 

After  all,  where  would  the  Stahlians  place 
this  simple  and  indivisible  being?  In  the 
brain  without  doubt.  But  then  how  does  it 
happen  that  an  animal  may  live,  and  the  mo- 
tion of  its  heart  continue  after  it  is  decapitated. 
Would  they  place  it  in  the  heart  itself?  But 
all  animals,  and  especially  those  of  cold  blood, 
live  a longer  or  shorter  time  after  the  heart  is 
cut  out.* 

Other  writers,  such  as  Abraham  Eus,f  Stce- 
lielin4  &c.  have  also  endeavoured  to  explain 
the  motions  of  the  heart;  but  their  systems, 

* For  an  exposition  and  refutation  of  this  system  see 
Haller’s  Element.  Physiolog.  Tom.  1,  p.  480—8,  and  Tom. 
4,  p.  517— 34. 

t Dissertatio  Physiol,  de  causa  vices  cordis  alternas  pro- 
ducente.  Lugd.  Batav.  1745. 

| Dissertatio  de  pulsibus.  Basilete,  1749. 


\ 


7 

almost  as  soon  forgotten  as  conceived,  do  not  de- 
serve to  detain  us. 

Those  gf  Boerhaave  and  Stahl  reigned  almost 
alone,  when  in  1752  Haller  published  his  ex- 
periments on  irritability.  These  experiments 
and  those  of  his  followers  tend  to  prove,  that 
the  contractile  power  belongs  essentially  to  the 
muscular  fibre.  That  property  which  Haller 
sometimes  speaks  of  under  the  name  of  vis 
insita,  sometimes  after  Glisson,  under  that  of 
irritability,  is  the  source  of  all  the  motions 
which  take  place  in  the  animal;  but  it  cannot 
produce  them  except  some  cause,  some  stimulus 
determines  it  to  act.  Thus  all  muscular  motion 
implies  two  things,  the  irritability  which  pro- 
duces the  contraction  of  the  muscle,  and  the 
stimulus  which  determines  the  irritability  to 
act.  The  irritability  is  every  where  the  same. 
It  only  varies  in  intensity  in  the  different  mus- 
cles ; but  it  does  not  obey  the  same  stimuli  in 
all  the  muscles.  The  nervous  power  is  the 
natural  stimulus  to  all  those  which  are  under 
the  influence  of  the  will ; and  it  is  by  exciting  or 
suspending  the  action  of  that  power  on  the 
irritability  of  such  or  such  muscles,  that  the  will 
causes  any  particular  part  to  act  or  to  he  at 
rest.  It  is  not  thus  with  the  muscles  of  invo- 
luntary motion;  these  are  affected  by  stimuli 
of  different  kinds,  which  are  appropriated  to 
their  different  functions,  and  altogether  different 


8 


from  the  nervous  power.  It  is  the  blood  which 
is  the  natural  stimulus  of  the  irritability  of  the 
heart:  alimentary  substances,  of  that  of  the 
intestinal  canal,  &c. 

We  easily  deduce  from  these  principles  the 
explanation  of  the  leading  circumstances  which 
we  observe  in  the  motions  of  the  heart.  Thus 
its  motions  are  involuntary,  because  they  are 
independent  of  the  nervous  system;  they  take 
place  without  interruption  during  life,  because 
the  irritability  which  produces  them  belongs 
essentially  to  the  fibres  of  the  heart,  and  the 
blood  which  excites  them  is  constantly  supplied 
to  this  organ  by  the  veins  as  it  is  carried  off 
by  -the  arteries.  The  systole  and  diastole  suc- 
ceed each  other  alternately  and  regularly, 
because  the  stimulus  of  the  blood  always  oc- 
casions the  former  both  in  the  auricles  and 
ventricles,  and  the  systole  itself,  by  expelling 
the  stimulus,  occasions  the  diastole,  which  re- 
news the  systole  by  allowing  access  to  new 
blood. 

Such  is  a summary  view  of  the  celebrated 
Hallerian  theory  of  irritability.  That  theory 
was  not  contrived  in  the  closet  like  the  others 
of  which  we  have  spoken : it  was  founded,  as 
we  have  said,  on  experiments  made  by  Haller 
himself,  and  by  the  most  distinguished  of  his 
scholars,  who  then  occupied,  or  have  since 
occupied,  the  first  rank  among  the  Anatomists 


9 


and  Physicians  of  the  last  age.  These  experi- 
ments, repeated  throughout  Europe,  found  al- 
most every  where  supporters ; but  they  found 
also  some  opponents  of  the  greatest  reputation. 
The  principal  cause  of  this  difference  of  opinion, 
and  that  respecting  which  authors  have  not  yet 
been  able  to  come  to  any  agreement,  is  the  ques- 
tion, whether  the  motions  of  the  heart  are  really 
independent  of  the  nervous  system. 

We  may  reduce  to  three  heads  the  facts  by 
which  the  school  of  Haller  has  supported  the 
affirmative.  1st.  If  we  interrupt  all  communi- 
cation between  the  heart  and  the  brain,  the 
only  source  of  nervous  power,  by  dividing  the 
nerves  which  go  to  the  heart,  the  spinal  mar- 
row in  the  neck,  or  even  by  decapitation,  the 
motions  of  the  heart  continue  as  before.  2d.  If 
we  cut  out  the  heart  of  a living  animal,  and 
place  it  on  a table,  it  continues  to  beat,  and 
sometimes  for  a long  time.  M.  de  Humboldt  has 
shewn  that  it  beats  more  strongly,  and  for  a 
longer  time,  when  it  is  suspended.  3d.  We 
always  produce  convulsions,  even  for  some  time 
after  death,  in  the  muscles  of  voluntary  motion, 
by  irritating  their  nerves,  either  mechanically  or 
in  any  other  way.  On  the  contrary,  the  irrita- 
tion of  the  cardiac  nerves  occasions  no  change 
in  the  motions  of  the  heart,  nor  re-calls  them 
when  they  have  ceased.  The  same  observation 

is  true  of  the  medulla  oblongata  and  spinal' 

4 


10 


marrow,  the  irritation  of  which  occasions  strong 
general  convulsions,  but  produces  no  effect  upon 
the  heart. 

These  facts  are  correct,  except  perhaps  those 
of  the  third  head,  respecting  which  there  is  some 
difference  of  opinion.  For  in  admitting  them, 
the  adversaries  of  irritability  have  asked,  why, 
if  the  nervous  power  has  no  action  on  the  heart, 
is  this  organ  supplied  with  nerves,  and  why 
is  it  so  evidently  subjected  to  the  influence  of 
the  passions  ? Haller  never  gave  any  satisfac- 
tory explanation  of  these  objections,  but  every 
thing  proves  that  he  felt  all  their  force.  When 
we  read  with  attention  all  that  he  has  said  of 
the  motions  of  the  heart,  in  his  dissertations 
on  irritability,*  and  above  all  in  his  great 
work  on  Physiology,!  we  are  struck  with  the 
contradictions  which  we  meet  with  in  them,  and 
which  makes  the  perusal  of  them  fatiguing. — 
Through  all  of  them  his  great  object  is  to 
prove,  that  the  motions  of  the  heart  are  inde- 
pendent of  the  nervous  system.  All  the  facts, 
all  the  experiments,  all  the  observations  which 
he  brings  forward,  tend  to  this  end;  and  yet 
he  seems  to  admit  in  several  places  that  the 
nerves  possess  an  influence  over  the  heart. — 

* Memoires  sur  la  nature  sensible  et  irritable  des  parties, 
etc.  Lausanne,  1756. — Opera  minora,  Tom.  1. 

t Element.  Physiol,  lib.  iv.  sect.  5,  et  lib.  xi.  sect.  5. 


11 


It  is  true  that  it  is  with  an  air  of  doubt  that  he 
admits  it,  and  confines  himself  to  saying,  that 
it  is  possible,  that  it  is  not  unlikely,  that  the 
heart  derives  a power  of  motion  from  the 
nerves.* * * §  These  contradictions  with  which  se- 
veral justly  celebrated  writers  have  reproach- 
ed him,  amongst  others  MM.  Prochaska,f 
Behrends,J  Ernest  Platner,§  &c.  proceed  evi- 
dently from  his  not  being  able  to  reconcile  the 
results  of  experiments  with  the  influence  of 
the  nervous  power  over  the  motions  of  the 
heart ; and,  in  rejecting  this  influence,  finding 
it  impossible  to  explain  the  use  of  the  cardiac 
nerves  and  the  effect  of  the  passions  on  the 
heart.  Here  is  the  great  difficulty  in  the  con- 
troversy of  which  we  speak.  Those  who,  like 
Fontana,  formally  rejected  all  intervention  of  the 
nervous  influence,  have  been  forced  to  admit 
that  the  nerves,  destined  to  convey  to  every 
other  part,  life,  feeling  and  motion,  have  no 
known  use  in  the  heart.  || 

* Ibid.  lib.  iv.  sect.  5,  p.  493,  et  alibi  passim. 

t Opera  minora  Viennse,  1800,  Tom.  II.  p.  90. 

t Yol.  3,  p.  4,  of  the  Collection  of  Ludwig,  entitled 
Scriptores  neurolog.  minores  selecti , Lipsise,  1791 — 5.  Four 
volumes,  in  4to. 

§ Vol.  2,  p.  266,  of  the  same  Collection. 

||  Memoires  sur  les  parties  sensibl.  et  irritab.  Tom.  3,  p. 
234.  See  also  Caldani,  ib.  p.  471,  and  Le  Traite  sur  le  venin 
de  la  vipere,  Tom.  II.  p.  169 — 171. 


12 


Sucli  consequences  evidently  disclose  the  in- 
sufficiency of  the  theory  of  Haller,  and  seve- 
ral of  his  followers  have  acknowledged  the 
necessity  of  some  modification  of  it,  and  admit 
the  nervous  power  to  be  one  of  the  principles 
on  which  irritability  depends.  They  are  thus 
enabled  to  assign  a use  to  the  nerves  of  the 
heart,  and  to  explain  the  influence  of  the  pas- 
sions on  this  organ.  But  when  they  have 
attempted  to  explain  why  the  interruption  of 
all  communication  between  the  brain  and  the 
heart  does  not  stop  the  motions  of  the  latter, 
they  have  been  obliged  to  abandon  the  gene- 
rally received  opinion,  which  regards  the  brain 
as  the  only  centre  and  source  of  nervous  power, 
and  have  admitted,  without  any  direct  proofs, 
that  that  power  is  generated  throughout  the 
whole  extent  of  the  nervous  system,  even  in 
the  smallest  nerves,  and  that  it  can  exist  for  a 
certain  time  in  the  nerves  of  any  part  inde- 
pendently of  the  brain.  Among  the  authors 
of  this  opinion,  the  learned  Professor  Prochaska 
is  one  of  those  who  has  given  the  best  account 
of  it.*  But  when  he  applies  it  to  the  motions 
of  the  heart,  and  attempts  to  explain  why  they 
are  independent  of  the  will  and  yet  influenced 

* Commentatio  de  functionibus  systematis  nervosi,  pub- 
lished in  the  third  fasciculus  of  the  Adnotationes  Academ. 
of  this  writer,  and  re-printed  at  Vienna  in  his  Opera  Minora, 
in  1800. 


13 


by  the  passions,  his  opinion  appears  undecided. 
He  has  recourse  to  the  ganglions,  and  hesitates 
what  function  to  ascribe  to  them.  Sometimes 
he  considers  them  as  knots,  as  ligatures,  so 
tight  as  to  intercept  all  communication  between 
the  heart  and  Sensorium  Commune , in  the  calm 
and  peaceful  state  of  the  system,  but  not  suf- 
ficient to  prevent  the  Sensorium  re-acting  more 
or  less  powerfully  on  the  heart  in  the  agitation 
of  the  passions.* * * §  Sometimes  he  seems  to  be- 
lieve that  the  interception  is  complete  and  con- 
stant, and  that  it  is  by  the  nerves  of  the  eighth 
pair  that  the  passions  affect  the  heart  ;f  and  he 
seems  to  adopt  the  opinion  of  Winslow, J re- 
newed by  Winterly  Johnstone,  ||  Unzer,Tf  Le- 
cat,**  Peffinger,f  f &c.  that  the  ganglions  are  so 
many  small  brains.  He  admits  at  the  same 
time  that  the  nerves  of  feeling  are  distinct  from 
those  of  motion,  so  that  the  heart  cannot  contract 
except  when  the  impression  of  the  stimulus  on 

* Opera  minora,  Tom.  2,  p.  165. 

t Ibid,  p.  167* 

| Exposit.  Anatom.  Traite  des  Nerfs,  § 364. 

§ Nov.  Inflam.  Theoria,  Viennee,  1767,  cap.  5,  p.  154. 

||  Essay  on  the  use  of  the  Ganglions,  1771. 

H Unzer  quoted  by  Prochaska  oper.  minor.  Tom.  2,  p. 
169. 

**  Traite  de  1’existence  de  la  nature  et  des  proprietes 
du  fluide  nerveux,  Berlin,  1765,  p.  225. 

tt  De  structura  nervorum,  Argentorati,  1782,  Sect.  1,  § 
34.  inserted  in  the  Collection  of  Ludwig,  vol.  1, 


14 


its  cavities  is  transmitted  to  the  ganglions  by  the 
nerves  of  feeling,  and  reflected  on  its  fibres  by 
the  nerves  of  motion.*  But  besides  that  this 
opinion,  even  by  the  author’s  confession,  is  only 
a conjecture,  it  supposes  on  the  one  hand,  that 
the  circulation  would  continue  after  the  destruc- 
tion of  the  spinal  marrow ; and  on  the  other, 
that  the  heart  would  cease  to  beat  at  the  moment 
when  its  communication  with  the  ganglions  and 
the  Plexus  is  interrupted.  Now  both  these  sup- 
positions are  contradicted  by  facts. 

These  fruitless  attempts  to  modify  the  theory 
of  irritability  by  the  intervention  of  the  nerv- 
ous power,  have  only  increased  the  zeal  of  some 
authors  to  maintain  that  theory  in  its  original 
purity,  and  as  the  use  of  the  nerves  of  the  heart 
was  among  the  most  embarrassing  objections 
to  it,  M.  Scemmerring,  one  of  the  most  pro- 
found Anatomists  of  Germany,  and  Behrends, 
one  of  his  most  distinguished  scholars,  main- 
tained, in  1792,  that  the  heart  has  no  nerves, 
and  that  all  those  Avhich  appear  to  enter  it  are 
expended  on  the  coats  of  the  coronary  arteries, 
without  the  fibres  of  the  heart  receiving  a single 
thread  ;f  an  opinion  which  far  from  removing 

* Opera  Minor.  Tom.  II.  p.  169. 

t Behrends  Dissertatio  qua  demonstratur  cor  ner\  is  ca- 
rere,  Moguntife,  1792,  inserted  in  the  third  voL  of  the  Col- 
lection of  Ludwig. 


15 


all  the  difficulties,  only  renders  the  influence  of 
the  passions  on  the  motions  of  the  heart  more 
inexplicable.  These  two  authors  maintain  that 
the  cardiac  nerves  support  and  increase  the  irri- 
tability of  the  coronary  arteries  ; but  the  exist- 
ence of  irritability  in  the  arteries  is  still  doubt- 
ful, and  were  it  demonstrated,  it  would  be  very 
strange  if  irritability  depended  on  the  nervous 
influence  in  the  arteries ; and  in  the  heart,  the 
most  irritable  of  all  the  organs,  it  were  wholly 
independent  of  this  influence. 

Science,  however,  has  cause  to  rejoice  at  the 
groundless  doubts  proposed  by  M.  Behrends 
respecting  the  cardiac  nerves,  since  they  have 
induced  the  learned  Scarpa  to  take  part  in  the 
dispute,  and  have  procured  for  us  his  excellent 
work  on  the  nerves  of  the  heart.*  M.  Scarpa 
proves  in  that  work  that  the  nerves  of  the 
heart  are  as  numerous,  and  are  distributed  in 
the  same  way,  as  in  other  muscles.  He  admits 
with  M.  Prochaska,  that  sensibility  and  irrita- 
bility are  essentially  united,  and  that  the  ner- 
vous influence  is  generated  throughout  the 
whole  extent  of  the  nerves ; but  he  does  not 
admit  that  the  ganglions  are  so  many  little 
brains.f  He  seems  to  believe  that  the  nerv- 

* Tab.  neurolog.  ad  illust.  hist.  anat.  cardiacorum  nervo- 
rum. &c.  Ticini,  1794. 

t Ibid,  § 30. 


16 


eus  influence,  such  as  it  exists  in  all  the  nerves, 
is  of  itself  sufficient  for  the  exercise  of  the 
different  functions,  and  that  it  only  wants  the 
stimulus  which  excites  it  to  action.  That  the 
stimulus  of  the  muscles  of  voluntary  motion 
comes  from  the  brain,  and  that  in  ordinary 
states  the  blood  is  the  stimulus  of  the  heart : but 
that  in  vivid  emotions  the  brain  also  becomes  a 
stimulus  to  this  organ.* 

According  to  this  opinion  the  heart  ought  to 
beat  in  the  same  manner,  and  with  the  same 
force,  after  decapitation,  after  the  destruction  of 
the  spinal  marrow,  and  after  it  is  removed  from 
the  body.  M.  Scarpa  himself  compares  the  beat- 
ing of  the  heart  in  apoplexy  to  that  which  we 
observe  when  it  no  longer  communicates  either 
with  the  brain  or  spinal  marrow. f But  we 
shall  see  in  the  sequel  that  it  is  very  different. 
We  must  not  omit  a very  important  remark  of 
this  author,  and  which  it  is  surprising  was  not 
sooner  made.  It  respects  the  insensibility  of 
the  heart  when  we  irritate  the  spinal  marrow 
and  the  cardiac  nerves.  M.  Scarpa  observes, 
that  that  insensibility  of  w hich  so  much  has 
been  said,  and  which  has  been  regarded  as  a 
demonstrative  proof  that  the  motions  of  the 
heart  do  not  depend  on  the  nerves,  proves  only 

* Ibid,  § 22,  24,  25,  26,  27,  2b. 

t Ibid,  § 25. 


17 

that  the  nerves  of  the  heart  are  not  of  the 
same  kind  with  those  of  the  muscles  of  volun- 
tary motion,  and  that  the  nervous  power  does 
not  in  them  obey  the  same  laws.* * * §  This  re- 
flection is  without  doubt  very  judicious,  and  it 
is  by  an  error  of  experimental  logic  that  we 
are  surprised  not  to  obtain  the  same  effects  from 
the  irritation  of  two  orders  of  nerves  wholly 
different. 

The  work  of  M.  Scarpa  did  not  induce  Dr. 
Scemmerringf  to  change  his  opinion,  nor  pre- 
vent Bichat  from  denying  that  the  nervous  power 
has  any  share  in  the  motions  of  the  heart4 
This  last  writer  maintains  the  existence  of  an 
animal  and  organic  life,  distinct  from  each 
other,  and  of  a nervous  system  for  each  of  these 
lives.  The  system  of  the  ganglions,  which 
he  regards  in  the  same  point  of  view  with  the 
authors  above  quoted,  as  small  brains,  belong 
to  the  organic  life,  and  the  cerebral  system  to 
the  animal  life.§>  To  be  consistent  with  him- 
self, Bichat  should  have  admitted,  like  M.  Pro- 
chaska,  that  the  heart,  the  centre  of  organic  life, 

* Ibid,  § 20. 

t Th.  Scemmerring  de  corporis  humani  fabrica.  Trajecti 
ad  Msenum,  1796.  Tom.  III.  p.  SO,  43,  46,  50,  et  ibid, 
1800,  Tom.  Y.  p.  43. 

$ Bichat.  Recherch.  Phys.  sur  la  vie  et  la  mort.  Paris, 
1800,  Part  II.  Art.  11,  § 1. 

§ Ibid,  Part  I.  Art.  6,  § 4-  Ibid,  Art.  1,  § S. 

5 


18 


derives  from  the  ganglions  the  principle  of  its 
motions  ; but  he  has  not  done  so.  It  is  chiefly 
the  galvanic  experiments  which  has  brought  him 
into  this  inconsistency,  because  he  had  attempt- 
ed in  vain  to  produce  contractions  in  the  heart 
by  galvanising  the  cardiac  nerves  ; experiments 
on  which  M.  Scemmerring  and  Behrends  had 
also  endeavoured  to  support  their  opinion. — 
These  experiments  may  always  succeed,  as  one 
of  us  found  in  1797?*  and  three  years  before  was 
found  by  Mr.  Fowler,  f 

Such  is  a short  but  faithful  account  of  the 
principal  systems,  by  m£ans  of  which  authors 
have  since  the  discovery  of  the  circulation  of 
the  blood  to  this  day,  attempted  to  explain 
the  motions  of  the  heart.  On  taking  a general 
view  of  them  we  remark,  that  in  all  those 
invented  before  Haller,^  the  nervous  power  is 
considered,  in  one  way  or  other,  as  one  of 
the  conditions  essential  to  the  production  of 

the  motions  of  the  heart : and  it  is  always  and 

* «/ 

only  in  the  brain  that  they  place  the  seat  of  it. 
The  cardiac  nerves,  therefore,  had  a determined 

* M.  de  Humboldt.  Experiences  sur  l*  irritation  de  la 
fibre  nerveuse  et  musculaire,  publiees  en  1797,  et  traduites 
en  Francjais  deux  ans  apres,  Tom.  I.  Chap.  9. 

t Experiments  on  Animal  Electricity,  by  Richard  Fowler. 
1794. 

t Also  in  those  of  Ens,  of  Stcehelin,  and  others  of  whom 
•we  have  spoken. 


19 


use  in  all  these  systems,  and  one  could  easily 
understand  why  the  heart  is  subject  to  the  em- 
pire of  the  passions  ; but  it  was  impossible  to 
explain  why  the  circulation  continues  in  acepha- 
lous animals,  and  why  in  experiments  on  ani- 
mals, the  interruption  of  all  communication  be- 
tween the  brain  and  the  heart  does  not  stop  the 
motions  of  the  latter.  Since  Haller,  irritability 
has  been  the  basis  <of  all  these  systems.  In  re- 
garding that  property  as  essential  to  the  fibre 
and  independent  of  the  nervous  influence,  the 
circulation  in  acephalous  animals,  and  the  dif- 
ferent phenomena  observed  in  the  experiments 
alluded  to,  present  nothing  that  is  not  easily  un- 
derstood ; but  the  use  of  the  nerves  of  the  heart 
and  the  influence  of  the  passions  on  that  organ 
become  inexplicable.  The  necessity  of  remov- 
ing these  difficulties  has  produced  two  parties 
among  the  supporters  of  irritability.  The  one, 
zealous  favourers  of  the  doctrine  of  pure  irrita- 
bility, called  to  their  aid  the  most  improbable 
hypotheses,  and  all  their  efforts  have  only  serv- 
ed to  prove  how  difficult  it  is  to  support  the 
cause  they  espouse.  The  other  confounded  the 
nervous  power  with  irritability,  which  they  con- 
sider as  one  of  the  functions  of  that  power  ; but 
they  have  been  obliged  to  admit,  either  with  re- 
spect to  the  seat,  or  the  manner  of  existence,  of 
the  nervous  power,  conditions,  which,  by  their 
own  confession,  are  far  from  being  demonstrated, 


2Q 


respecting  yffiich  they  are  not  agreed,  and  which, 
in  the  application  they  make  of  them  to  the  mo- 
tions of  the  heart,  either  do  not  wholly  remove 
the  old  difficulties  or  create  new  ones. 

One  may  easily  see  why  so  little  progress  has 
been  made  in  this  great  and  long  disputed  ques- 
tion. If  we  examine  all  that  has  been  said  on 
the  subject  since  the  days  of  Haller,  we  shall 
find,  that  both  sides  have  constantly  brought  for- 
ward nearly  the  same  facts,  the  same  experi- 
ments, and  the  same  reasonings.  The  only 
new  experiments  are  the  applications  of  galvan- 
ism to  stimulate  the  cardiac  nerves  ; and  they 
are  only  new  in  appearance,  for  from  the  time  of 
Haller  electricity  has  been  employed  with  the 
same  view.*  It  is  evident  that  science  had 
nothing  to  expect  from  our  pursuing  a path 
trodden  for  nearly  sixty  years  by  so  many  cele- 
brated men.  It  was  necessary  to  open  new 
roads ; it  was  necessary  to  find  or  invent  new 
modes  of  interrogating  nature.  It  was,  above 
all,  necessary  to  introduce  into  physiological  ex- 
periments, that  precision  and  severe  logic  to 
which  other  branches  of  physical  science  have, 
in  our  days,  owed  so  great  progress.  It  is  this 
which  the  author  of  the  memoir  before  us  lias 
done. 


* See,  amongst  others,  Mem.  sur  les  parties  sensib.  et  ir- 
ritab.  Tom.  Ill,  p.  214. 


2i 


It  was  not  the  original  object  of  M.  le  Cfallois 
to  explore  the  cause  of  the  motions  of  the  heart. 
He  had  adopted  the  theory  of  Haller  on  this 
subject,  when  experiments  undertaken  with  other 
views  led  him  to  the  singular  conclusion,  that 
it  was  impossible  for  him  to  understand  his  own 
experiments,  without  determining  whether  the 
nervous  power  influences  the  motions  of  the 
heart ; and  if  so,  in  what  way  it  has  this  effect. 
To  make  his  work  better  understood,  we  shall 
relate  on  what  occasion,  and  by  what  chain  of 
facts  and  reasonings  he  was  led  to  engage  in  this 
inquiry. 

A peculiar  case  of  labour  some  years  ago 
excited  in  him  a wish  to  know  how  long  a full- 
grown  foetus  can  live  without  breathing,  after 
all  communication  between  it  and  the  mother 
has  ceased.  That  question,  curious  in  itself, 
and  of  the  first  importance  in  the  practice  of 
midwifery  and  medical  jurisprudence,  had  hard- 
ly been  touched  upon  by  authors.  M.  le  Gfal- 
lois  undertook  to  resolve  it  by  direct  expe- 
riments on  animals ; and  that  the  solution 
might  be  generally  applicable,  and  extend  to 
as  many  cases  as  possible,  he  placed  the  foetus 
of  animals  in  various  situations  similar  to  those 
in  which  the  human  foetus  is  occasionally  placed, 
when  it  ceases  to  communicate  with  the  mother. 
Among  these  there  is  one  which  occurs  too  often, 
namely,  the  foetus  suffering  decollation  from  arti- 


22 


ficial  delivery  by  the  feet.  The  author  wished 
to  know  what  happens  to  the  foetus  in  this  case, 
whether  it  perishes  at  the  instant  of  decollation, 
and  how  death  takes  place.  He  found  that  the 
trunk  retains  its  life,  and  that  if  hemorrhage  be 
prevented,  by  throwing  a ligature  round  the  ves- 
sels of  the  neck,  it  dies  in  the  same  time  and  with 
the  same  symptoms  as  if,  without  taking  off  the 
head,  respiration  had  been  interrupted ; and  what 
completely  demonstrated  to  him  that  a decapitated 
animal  is  in  fact  suffocated,  is,  that  we  may  at 
pleasure  prolong  its  existence  by  inflating  the 
lungs  to  supply  the  place  of  natural  respiration. 

M.  le  Gallois  concluded  from  these  facts,  that 
decollation  proves  fatal  by  destroying  the  motions 
of  inspiration,  and  that  consequently  the  power 
on  which  these  motions  depend  is  in  the  brain  ; 
but  that  that  on  which  the  life  of  the  trunk  de- 
pends is  in  the  trunk  itself.  Endeavouring  to  as- 
certain the  precise  seat  of  each  of  these  powers, 
he  found  that  that  on  which  the  motions  of  inspi- 
ration depend  resides  in  that  part  of  the  medulla 
oblongata  from  which  the  eighth  pair  of  nerves 
take  their  rise ; and  that  on  which  the  life  of  the 
trunk  depends,  in  the  spinal  marrow.  It  is  not 
by  all  the  spinal  marrow  that  every  part  of  the 
body  is  animated,  but  only  by  that  portion  from 
which  it  receives  its  nerves ; so  that  in  destroying 
any  particular  part  of  the  spinal  marrow,  we  only 
destroy  life  in  those  parts  of  the  body  which  cor 


23 


respond  to  that  part.  Besides,  if  we  interrupt 
the  circulation  in  any  particular  part  of  the  spinal 
marrow,  life  is  weakened,  and  soon  extinguished 
in  all  the  parts  which  receive  nerves  from  it. 
There  are,  therefore,  two  ways  of  destroying  life 
in  any  part  of  an  animal ; the  one  destroying  that 
part  of  the  spinal  marrow  from  which  it  receives 
its  nerves,  the  other  interrupting  the  circulation 
in  this  part  of  the  spinal  marrow. 

It  hence  results,  that  two  conditions  are  neces- 
sary to  preserve  the  life  of  any  part  of  the  body, 
viz.  the  integrity  of  the  corresponding  part  of  the 
spinal  marrow,  and  the  circulation  of  the  blood, 
and  consequently  that  we  may  preserve  life  in 
any  part  of  an  animal  as  long  as  we  can  preserve 
in  it  these  two  conditions.  We  may,  for  exam- 
ple, preserve  the  life  of  the  anterior  parts  after 
that  of  the  posterior  parts  is  destroyed,  by  de- 
stroying the  corresponding  portion  of  the  spinal 
marrow,  or  vice  versa. 

M.  le  Gallois,  whose  constant  practice  was  to 
seek  in  direct  experiments  a confirmation  of  the 
consequences  which  he  deduced  from  preceding 
ones,  wished  to  know  if  in  fact  it  is  possible  to 
make  any  particular  part  live  after  the  others  are 
dead.  In  a rabbit  twenty  days  old  he  destroyed 
all  the  lumbar  portion  of  the  spinal  marrow.  This 
operation  occasioning  no  immediate  injury  to  the 
rest  of  the  spinal  marrow,  and,  according  to  the 
theory  of  Haller,  the  circulation  not  being  affect- 


ed  by  rt,  he  had  every  reason  to  expect,  reason- 
ing from  the  preceding  experiments,  that  the  ani- 
mal would  have  lived  for  a considerable  length 
of  time,  and  that  it  would  only  have  died  in  con- 
sequence of  the  symptoms  produced  by  so  severe 
an  injury  ; but  the  respiration  ceased  in  a minute 
or  two,  and  in  less  than  four  minutes  it  shewed  no 
sign  of  life.  This  experiment  was  repeated  seve- 
ral times  with  the  same  result,  nor  was  it  possible 
to  prevent  it.  Thus  it  was  proved,  that  a rabbit 
of  twenty  days  old  cannot  survive  the  loss  of  the 
lumbar  portion  of  the  spinal  marrow  ; which  ap- 
peared the  more  surprising,  because  rabbits  of 
this  age  continue  to  live  very  well  after  decapita- 
tion, that  is,  after  the  total  loss  of  the  brain.  This 
fact,  which  the  author  could  not  reconcile  with  his 
preceding  experiments,  led  him  to  discover,  that 
the  power  on  which  the  action  of  the  heart  de- 
pends fie  principe  des  forces  du  coeurj  resides 
in  the  spinal  marrow. 

M.  le  Gallois  then  ascertained  that  the  de- 
struction of  either  the  dorsal  or  cervical  portiou 
of  the  spinal  marrow  was  fatal  to  rabbits  of 
twenty  days  old,  even  in  a shorter  time  than 
that  of  the  lumbar  portion,  in  about  two  mi- 
nutes. He  found  that  the  same  experiments  re- 
peated on  rabbits  of  different  ages  did  not  u ve 
the  same  results.  In  general  the  destruction 
of  the  lumbar  portion  was  not  suddenly  fatal 
to  rabbits  under  ten  days  old,  and  some  at  the 


25 


age  of  fifteen  days  survived  it.  Beyond  twen- 
ty days  old  the  effect  is  the  same  as  a t this 
age.  Very  young  rabbits  continued  to  live  after 
the  destruction  either  of  the  dorsal  or  cervical 
portion,  but  for  a shorter  time  ; and  in  a smaller 
number  of  cases,  after  the  destruction  of  the 
latter  than  after  that  of  the  dorsal  portion.  None 
after  the  age  of  fifteen  days  survived  the  destruc- 
tion of  either. 

In  all  those  partial  destructions  of  the  spinal 
marrow,  even  where  the  death  is  sudden,  it  is  in- 
stantaneous only  in  the  parts  which  receive  their 
nerves  from  the  destroyed  part,  and  only  extends 
to  the  rest  of  the  body  at  the  end  of  a certain 
time  ; but  this  time  is  fixed,  and  no  means  can 
prolong  it.  It  is  the  same  in  animals  of  the  same 
kind  and  of  the  same  age ; and  the  longer,  the 
nearer  the  animal  is  to  the  time  of  its  birth.  For 
example,  when  the  cervical  part  of  the  spinal 
marrow  is  destroyed  in  rabbits,  life  is  instantly 
lost  in  the  whole  of  the  neck  ; but  it  continues  in 
the  head,  as  appears  from  the  gaspings  it  excites; 
it  continues  also  in  the  parts  below  the  shoulder, 
as  the  continuance  of  their  feeling  and  voluntary 
motion  shews.  In  the  first  day  after  birth,  the 
gaspings  continue  about  twenty  minutes,  the  sen- 
sibility and  motion  of  the  rest  of  the  body  fifteen 
minutes.  At  the  age  of  fifteen  days,  the  duration 
of  the  gaspings  does  not  exceed  three  minutes  ; 

that  of  sensibility  and  motion  two  and  a half.  In 

6 


26 


fine,  at  the  age  of  thirty  days  the  gaspings  cease 
in  a minute  and  a half,  and  the  sensibility  in  a 
minute.  After  the  destruction  of  the  dorsal  por- 
tion of  the  spinal  marrow,  it  is  the  chest  and  not 
the  neck  which  is  instantly  struck  with  death.  In 
other  respects  the  phenomena  and  their  duration 
are  the  same.  If  the  three  portions  of  the  spinal 
marrow  are  destroyed  at  once,  the  gaspings,  the 
only  signs  of  life  which  then  remain,  have  still, 
at  the  different  ages,  the  durations  just  pointed 
out. 

The  author,  who  had  so  often  decapitated  rab- 
bits of  different  ages,  had  always  remarked  that 
the  head,  separated  from  the  body,  continued  to 
gasp  during  a time  determined  by  the  age.  This 
time  was  evidently  the  same  as  after  the  de- 
struction of  the  spinal  marrow.  Now  it  is  evi- 
dent that  after  decapitation  there  can  be  no  longer 
any  circulation  in  the  head,  and  that  the  gasp- 
ings which  take  place  in  that  case  can  only  con- 
tinue for  the  time  during  which  life  may  exist  in 
the  brain,  after  the  total  ceasing  of  the  circula- 
tion. This  was  the  first  indication  which  M.  le 
Gallois  had,  that  when  the  partial  destruction 
of  the  spinal  marrow  occasions  death  throughout 
all  the  rest  of  the  body,  it  is  because  it  suddenly 
arrests  the  circulation.  To  assure  himself  of  this, 
he  cut  out  the  heart  at  the  base  of  the  great  ves- 
sels, in  rabbits  of  every  fifth  day  old  from  birth 
to  the  age  of  a month : and  having  noted  with 


care  the  duration  of  the  different  signs  of  life 
from  the  moment  at  which  the  circulation  was 
thus  stopped,  he  found,  that  their  duration  was 
precisely  the  same  as  after  the  destruction  of  the 
spinal  marrow.  He  might  have  considered  this 
coincidence  as  sufficient  to  decide  the  question ; 
but  he  wished  to  ascertain  in  a more  direct  man- 
ner if  the  circulation  actually  ceases  at  the  mo- 
ment the  spinal  marrow  is  destroyed.  The  ab- 
sence of  liemorrhagy  and  the  emptiness  of  the 
arteries  were  the  most  evident  signs  that  he 
could  have  of  the  circulation  having  ceased  ; and 
he  found,  in  fact,  that  soon  after  the  above  ope- 
ration, the  carotids  were  found  empty,  and  the 
amputation  of  the  limbs  occasioned  no  hemorr- 
liagy,  though  performed  near  to  the  trunk,  and 
before  life  was  extinct  in  the  parts  of  which  the 
spinal  marrow  had  not  been  destroyed.  In  a 
word,  all  the  signs  which  shew  the  state  of  the 
circulation  demonstrated  to  him,  that  when  the 
destruction  of  any  part  of  the  spinal  marrow  sud- 
denly occasions  death  in  the  rest  of  the  body,  it 
is  by  stopping  this  function,  and  this  effect  takes 
place  not  because  the  motion  of  the  heart  imme- 
diately ceases,  but  because  it  is  no  longer  capa- 
ble of  throwing  the  blood  even  into  the  carotids. 

Hence  it  follows,  that  it  is  in  the  spinal  mar- 
row that  the  power  on  which  the  motion  of  the 
heart  depends  resides,  and  in  the  whole  of  it, 
since  the  destruction  of  any  one  of  its  three  por- 


tions  is  capable  of  stopping  the  circulation.  It  also 
follows,  that  each  portion  of  the  spinal  marrow 
influences  life  in  two  different  ways  ; by  the  one 
it  is  essential  to  the  existence  of  life  in  the  parts 
which  receive  nerves  from  it ; by  the  other,  it 
preserves  it  throughout  the  body  in  general,  by 
contributing  to  furnish  to  the  organs  which  re- 
ceive nerves  from  the  great  sympathetic,  and  par- 
ticularly to  the  heart,  the  life  and  power,  fie 
pvincipe  lie  force  et  de  vie,J  necessary  to  the 
performance  of  their  functions. 

Thus  we  see,  that  to  make  the  anterior  or  pos- 
terior parts  of  an  animal  live  after  killing  the 
rest  of  the  body,  by  destroying  the  corres- 
ponding parts  of  the  spinal  marrow,  we  must 
prevent  the  destruction  of  these  parts  from  stop- 
ping the  circulation.  Now  this  is  easily  done  by 
diminishing  the  sum  of  the  forces,  which  the 
heart  must  impart  for  the  support  of  the  circula- 
tion, in  proportion  as  we  diminish  the  power 
which  it  receives  from  the  spinal  marrow.  It 
is  sufficient  for  this  purpose  to  diminish  by  liga- 
tures, thrown  round  the  arteries,  the  extent  of 
the  parts  to  which  the  heart  sends  the  blood. — 
We  have  seen,  for  example,  that  the  destruction 
of  the  lumbar  part  of  the  spinal  marrow  is  quick- 
ly fatal  to  rabbits  at  or  beyond  the  age  of  twenty 
days;  but  this  is  not  the  case  if  we  previously 
throw  a ligature  round  the  ventral  aorta  between 
the  cceliac  and  anterior  mesenteric  arteries. 


29 


The  application  of  this  principle  to  other  parts 
of  the  body  leads  to  the  singular  conclusion,  that 
in  order  to  maintain  life  in  rabbits  of  a certain 
age,  after  the  destruction  of  the  cervical  part  of 
the  spinal  marrow,  we  must  previously  cut  off  the 
head.  They  certainly  die  if  this  part  of  the  spi- 
nal marrow  is  destroyed  without  previous  decapi- 
tation. This  fact  ceases  to  surprise,  when  we 
reflect  that  by  decapitation,  we  lessen  by  the  head 
the  extent  of  the  circulation,  and  that  by  that 
means  the  heart  having  need  of  less  force  to  sup- 
port the  circulation,  we  may  enfeeble  it  by  the  de- 
struction of  the  cervical  part  of  the  spinal  mar- 
row, without  destroying  the  circulation. 

One  may  easily  conceive  that  any  other  opera- 
tion capable  of  suspending  or  considerably  en- 
feebling the  circulation  in  any  part  of  an  animal 
may  produce  a similar  effect ; and  enable  us  in 
like  manner,  to  destroy  such  a portion  of  the  spi- 
nal marrow,  as  would  have  been  fatal  without 
this  previous  operation.  This  is  what  happens 
in  the  partial  destruction  of  the  spinal  marrow 
itself.  It  has  two  effects  on  the  circulation ; by 
the  one  it  enfeebles  it,  generally  by  depriving  the 
heart  of  that  share  of  its  power  which  it  receives 
from  the  part  of  the  spinal  marrow  that  has  been 
destroyed  ; by  the  other,  without  wholly  destroy- 
ing the  circulation  in  the  parts  which  are  thus  de- 
prived of  life,  it  in  a great  degree  lessens  it  in  a 


30 


way  in  some  measure  similar  to  the  effect  of  liga- 
tures thrown  round  the  arteries  of  these  parts. 
But  this  effect  is  not  remarked  till  a few  minutes 
after  the  destruction  of  the  spiual  marrow.  Thus 
it  is  the  destruction  of  the  first  part  of  the  spinal 
marrow  which  enables  us  to  destroy  a second. 
This  a third  and  so  on.  For  example,  when, 
by  decapitating  a rabbit,  Ave  are  enabled  to  de- 
stroy the  cervical  part  of  the  spinal  marrow,  the 
destruction  of  that  part  in  a certain  number  of  mi- 
nutes enables  us  to  destroy  the  fourth  part  of  the 
dorsal  portion  of  the  spinal  marrow,  and  thus  by 
continuing  to  destroy  parts  of  similar  extent,  by 
intervals,  we  may  at  length  destroy  the  whole  of 
this  portion  of  the  spiual  marrow  without  stop- 
ping the  circulation,  which  is  then  supported  by 
the  lumbar  portion  only. 

We  may  collect  from  what  has  just  been  said, 
that  in  rabbits,  each  portion  of  the  spinal  marrow 
bestows  on  the  heart  power  sufficient  to  support 
the  circulation  in  all  those  parts  which  correspond 
to  that  portion,  and  consequently,  that  in  cutting 
a rabbit  transversely,  it  would  be  possible  to 
make  each  portion  live  for  an  indefinite  time,  if  the 
lungs  and  the  heart,  necessary  for  the  formation 
and  circulation  of  arterial  blood,  could  make  part 
of  it.  But  they  can  only  make  part  of  the  chest, 
and  one  may  very  well  maintain  the  life  of  the 
chest  alone  and  insulated,  after  having  cut  off 


31 


both  the  anterior  and  posterior  parts,  and  prevent- 
ed hemorrhagy  by  proper  ligatures,  and  that  even 
in  rabbits  thirty  days  old  or  more. 

Such  are  the  principal  results  of  M.  le  Gallois’ 
researches,  results  which  arise  one  from  the  other, 
and  mutually  supporting  each  other,  are  founded 
on  direct  experiments,  made  with  a precision  hi- 
therto unknown  in  Physiology.  We  are  now 
going  to  relate  such  of  those  experiments  as  the 
author  repeated  in  our  presence.  We  devoted  to 
these  repetitions  three  meetings,  each  of  several 
hours  duration  : and,  in  order  to  avoid  all  preci- 
pitation, and  to  give  us  time  to  weigh  the  facts  at 
leisure,  we  allowed  a week  to  intervene  between 
the  meetings. 

Experiments  repeated  before  the  Committee  of 
the  Institute. 

We  shall  divide  them  into  two  parts  ; the  first 
will  comprehend  those  which  tend  to  prove  that 
the  origin  of  all  the  motions  of  inspiration  reside 
in  that  part  of  the  medulla  oblongata  which  gives 
rise  to  the  eighth  pair  of  nerves.  In  the  second 
we  shall  relate  those  whose  object  is  to  prove  that 
the  heart  derives  its  power  from  the  spinal 
marrow. 


32 


1st.  Experiments  relating  to  the  power  on  which 
the  motions  of  inspiration  depend. 

The  author,  in  a rabbit  of  five  days  old,  detach- 
ed the  larynx  from  the  os  hyoides,  and  exposed 
the  glottis  that  we  might  observe  its  movements  ; 
after  which  he  opened  the  head,  and  first  extract- 
ed the  cerebrum  and  then  the  cerebellum.  After 
these  operations  the  inspirations  continued  ; they 
were  each  characterised  by  four  simultaneous 
movements,  namely,  a gasping,  the  opening  of  the 
glottis,  the  elevation  of  the  ribs,  and  the  contrac- 
tion of  the  diaphragm ; these  four  movements  hav- 
ing been  observed,  and  found  to  continue  for  a 
certain  time,  according  to  the  age  of  the  animal, 
the  author  extracted  the  medulla  oblongata,  and 
in  a moment  these  movements  ceased  altogether. 
The  portion  of  the  medulla  oblongata  which  was 
extracted  extended  to  the  occipital  hole,  and  in- 
cluded the  origin  of  the  eighth  pair  of  nerves. 

The  same  experiment  was  repeated  on  another 
rabbit  of  the  same  age,  with  this  difference,  that 
after  the  extraction  of  the  cerebrum  and  cerebel- 
lum, instead  of  removing  so  large  a portion  of  the 
medulla  oblongata  all  at  once,  it  was  extracted 
successively,  by  portions  of  about  the  thickness  of 
three  millimetres.  The  four  motions  of  inspira- 
tion continued  after  the  extraction  of  the  three 
first  slices,  but  ceased  immediately  after  that  of 


33 


the  fourth ; we  found  that  the  third  slice  termi- 
nated at  the  posterior  part,  and  very  near  to  the 
pons  varolii,  and  that  the  fourth  embraced  the 
origin  of  the  nerves  of  the  eighth  pair. 

This  experiment  repeated  on  other  rabbits  con- 
stantly gave  the  same  result. 

The  same  experiment  was  made  on  a cat  five 
weeks  old,  except  that  before  the  medulla  oblon- 
gata was  removed  by  slices  the  two  recurrent 
nerves  were  divided.  The  glottis  immediately 
closed  and  remained  immoveable,  but  the  three 
other  motions,  namely,  the  gaspings,  the  eleva- 
tion of  the  ribs,  and  the  contractions  of  the  dia- 
phragm continued,  and  only  ceased  at  the  mo- 
ment when  that  portion  of  the  medulla  oblongata, 
in  which  the  eighth  pair  of  nerves  originate,  was 
removed. 

It  is  evident  that  if  in  place  of  destroying  that 
part  from  which  all  the  motions  of  inspiration 
are  derived,  one  only  cuts  off  the  communication 
between  it  and  the  organs  which  perform  these 
motions,  he  will  produce  the  same  effect ; that  is 
to  say,  will  stop  those  motions  whose  organs 
have  no  longer  any  communication  with  the  part 
in  question.  This  is  what  we  have  just  seen 
happen  in  the  cat,  in  which  the  division  of  the 
recurrent  nerves  stopped  the  motions  of  the  glot- 
tis without  stopping  the  other  three  motions.  In 
order  to  suspend  these  it  is  sufficient  to  observe 
hoAv  their  organs  communicate  with  the  medulla 

7 


34 


oblongata.  Now  it  is  clear  that  it  is  by  the  in- 
tercostal nerves,  and  consequently  by  the  spinal 
marrow,  that  the  medulla  oblongata  acts  upon 
the  muscles  which  raise  the  ribs,  and  that  it  is 
by  the  phrenic  nerves,  and  consequently  by  the 
spinal  marrow  also,  that  it  acts  on  the  dia- 
phragm. In  dividing  the  spinal  marrow  about 
the  last  cervical  vertebra,  and  below  the  origin  of 
the  phrenic  nerves,  one  ought  therefore  to  stop 
the  motions  of  the  ribs,  but  not  those  of  the  dia- 
phragm : and  in  dividing  the  spinal  marrow  be- 
tween the  occiput  and  the  origin  of  the  phrenic 
nerves,  we  ought  to  destroy  at  once  the  motions 
of  the  ribs  and  those  of  the  diaphragm,  and  this 
is  in  fact  what  happens.  The  author,  after  the 
motions  of  the  thorax  had  been  well  observed  in 
a rabbit  about  ten  days  old,  divided  the  spinal 
marrow  about  the  seventh  cervical  vertebra. 
Such  of  these  motions  as  depend  on  the  eleva- 
tion of  the  ribs,  immediately  ceased,  but  the  con- 
traction of  the  diaphragm  continued.  He  then 
divided  the  spinal  marrow  about  the  first  cervical 
vertebra,  and  immediately  the  diaphragm  ceased 
to  contract.  Lastly,  he  divided  the  eighth  pair 
of  nerves  about  the  middle  of  the  neck,  and  the 
motions  of  the  glottis  ceased.  Thus  of  the  four 
motions  of  inspiration  there  remained  only  the 
gaspings,  which  shewed  that  the  medulla  ob- 
longata still  preserved  the  power  to  produce  all 
the  motion,  and  that  it  only  failed  to  produce  the 


35 


other  three  because  it  no  longer  had  any  commu- 
nication with  their  organs.  We  ought  to  observe 
here;  that  several  authors,  amongst  others  Arne- 
mann,  before  M.  le  Gallois,  had  observed  that 
the  division  of  the  spinal  marrow  only  stopped 
the  motions  of  the  diaphragm  when  it  was  made 
between  the  occiput  and  the  origin  of  the  phrenic 
nerves  ; but  these  authors  regarded  the  brain  as 
the  only  source  of  life,  and  of  all  the  motions  of 
the  body.  They  thought,  accordingly,  that  the 
division  of  the  spinal  marrow  instantly  paralyzed 
all  parts  of  the  body  whose  nerves  arose  from 
the  spinal  marrow  below  the  part  at  which  it 
was  divided,  and,  therefore,  that  when  the  di- 
vision was  made  near  the  occiput  the  diaphragm 
ceased  to  contract,  because  it  partook  of  the  pa- 
ralysis of  all  the  parts  below  the  division.  But 
M.  le  Grallois  has  demonstrated,  that  the  division 
of  the  spinal  marrow,  made  about  the  first  or  last 
cervical  vertebra,  only  stops  the  motions  of  in- 
spiration, and  allows  to  remain  throughout  the 
body  both  feeling  and  voluntary  motion.  This 
distinction  is  essential.  No  person  made  it  be- 
fore him. 

It  is  not  only  in  warm  blooded  animals  that 
these  experiments  produce  the  results  which  we 
have  described.  To  prove  that  these  results  be- 
long to  the  general  laws  of  the  animal  economy, 
and  that  the  nervous  power  obeys  the  same  laws 
in  all  vertebral  animals,  the  author  took  a frog, 


36 


and  after  having  remarked  that  in  these  animals, 
which  have  neither  ribs  nor  diaphragm,  there  are 
but  two  kinds  of  motions  of  inspiration,  namely, 
those  of  the  glottis,  which  opens  in  the  form  of  a 
lozenge,  and  those  of  the  throat,  which  is  alter- 
nately raised  and  lowered,  he  cut  off  the  anterior 
half  of  the  brain,  the  two  motions  continued  ; he 
then  destroyed  about  the  half  of  that  which  re- 
mained ; the  motions  still  continued.  In  fine,  he 
carried  the  destruction  of  the  brain  as  far  as  the 
occiputal  hole,  and  the  two  motions  instantly 
ceased.  In  another  frog  he  divided  the  spinal 
marrow  about  the  third  vertebra,  the  motions  of 
inspiration  continued.  In  a third  frog  it  was  di- 
vided between  the  occiput  and  the  first  vertebra, 
the  motion  of  the  throat,  which  represents  that  of 
the  diaphragm,  immediately  ceased.  After  these 
two  last  experiments  the  frogs  were  and  remain- 
ed alive,  both  in  the  head  and  the  rest  of  the  bo- 
dy ; but  they  could  not  govern  their  motions,  and 
in  this  respect  were  in  the  same  state  as  the  first 
frog,  whose  brain  had  been  destroyed. 

%d.  Experiments  relative  to  the  principle  on 
which  the  power  of  the  heart  depends. 

The  author  has  already  proved  that  life  always 
continues  for  a certain  time,  even  in  warm  blood- 
ed animals,  after  the  total  ceasing  of  the  circula- 
tion, and  that  the  length  of  this  time  is  influenced 


37 


by  the  age  of  the  animal.  He  opened  the  chest 
and  cut  out  the  heart  of  a rabbit  of  five  or  six 
days  old  ; he  did  the  same  in  another  of  ten  days 
old.  In  the  first  the  gaspings  ceased  in  seven 
minutes,  and  the  sensibility  in  four  after  the  ex- 
cision of  the  heart.  In  the  second  the  gaspings 
lasted  only  four  minutes  and  the  sensibility  only 
three.  The  cervical  and  a small  portion  of  the 
dorsal  part  of  the  spinal  marrow  were  then  de- 
stroyed in  another,  rabbit  of  the  same  litter  with 
the  last,  and  immediately  afterwards  the  lungs 
were  inflated ; notwithstanding  this  assistance  the 
gaspings  ceased  at  the  end  of  three  minutes  and 
a half,  and  the  sensibility  in  a little  more  than 
two  and  a half ; periods  which  coincide,  we  see, 
to  nearly  half  a minute  with  those  observed  after 
the  excision  of  the  heart. 

In  order  to  prove  that  in  this  experiment  it  is 
really  by  stopping  the  circulation  that  the  de- 
struction of  a part  of  the  spinal  marrow  destroys 
the  life  of  the  rest  of  the  body,  the  author  divid- 
ed the  spinal  marrow  of  a rabbit  of  the  same  age 
with  the  two  last,  near  the  occiput.  After  this 
division  the  carotid  arteries  were  black,  but  round 
and  full,  and  on  the  amputation  of  a limb,  black 
blood  flowed ; having  inflated  the  lungs,  the  caro- 
tids quickly  regained  a fine  red  colour,  and  blood 
also  flowed  from  the  limb  of  the  same  colour. 
These  appearances  left  no  doubt  that  the  circula- 
tion continued  after  the  division  of  the  spinal 


38 


marrow  near  the  occiput.  The  author  then  de- 
stroyed in  this  rabbit  the  same  portion  of  the  spi- 
nal marrow  as  in  the  preceding.  The  carotids 
instantly  became  flaccid,  and  soon  appeared  emp- 
ty and  flat.  The  two  thighs  amputated  in  less 
than  two  minutes  after  the  destruction  of  the  spi- 
nal marrow  did  not  supply  a drop  of  blood. 

The  destruction  of  the  cervical  part  of  the  spi- 
nal marrow  in  several  other  rabbits,  from  twenty 
to  thirty  days  old,  gave  precisely  the  same  re- 
sults, that  is  to  say,  the  carotids  soon  appeared 
empty,  and  no  blood  flowed  on  the  amputation  of 
the  limbs  ; and  notwithstanding  the  most  careful 
inflation  of  the  lungs,  the  signs  of  life  remained 
no  longer  than  after  the  excision  of  the  heart,  ac- 
cording to  the  tables  which  M.  le  Gtallois  has 
given  of  the  different  ages  in  his  paper. 

The  results  were  the  same  with  respect  to  the 
emptiness  of  the  carotid  arteries,  the  absence  of 
hemorrhagy,  and  the  duration  of  life  after  the  de- 
struction of  the  dorsal  part  of  the  spinal  marrow. 

The  destruction  of  the  lumbar  part  of  the  spi- 
nal marrow  in  rabbits  of  four  and  five  weeks  old 
gave  similar  results,  with  this  only  difference, 
that  the  circulation  did  not  stop  immediately,  as 
after  the  destruction  of  the  cervical  and  dorsal 
parts  of  the  spinal  marrow ; but  at  the  end  of 
about  two  minutes,  and  in  one  case  at  the  end  of 
four  minutes,  which  proves  that  the  action  of  the 
lumbar  part  of  the  spinal  marrow  upon  the  heart. 


39 


though  evident  and  very  great,  is  not  so  imme- 
diate as  that  of  each  of  the  other  portions. 

After  having  proved  by  these  experiments  that 
the  circulation  depends  on  all  parts  of  the  spinal 
marrow,  the  author  shewed  us  that  there  is  none 
of  these  portions  which  may  not  be  destroyed 
with  impunity,  if  we  confine  to  a certain  space 
the  parts  to  which  the  heart  sends  the  blood. — 
After  opening  the  belly  of  a rabbit  six  weeks 
old,  he  threw  a ligature  round  the  aorta,  between 
the  cseliac  and  anterior  mesenteric  arteries,  after 
which  he  destroyed  the  whole  of  the  lumbar  part 
of  the  spinal  marrow.  This  rabbit  continued 
quite  alive,  supporting  itself  upon  its  fore  legs, 
and  holding  up  its  head  more  than  half  an  hour 
afterwards,  when  the  Committee  finished  their 
sitting,  while  another  rabbit  of  nearly  the  same 
age,  used  for  the  sake  of  comparison,  in  which 
the  lumbar  portion  of  the  spinal  marrow  had  been 
destroyed  without  securing  the  aorta,  died  in  less 
than  two  minutes. 

M.  le  Gallois  then  made  the  experiment  of 
destroying  the  cervical  portion  of  the  spinal  mar- 
row, the  action  of  which  upon  the  heart  is  more 
immediate,  and  still  more  considerable  than  the 
lumbar,  in  rabbits  of  five  or  six  weeks  old,  with- 
out stopping  the  circulation.  After  having  de- 
capitated the  animal  with  the  ordinary  precau- 
tion, he  performed  artificial  inspiration  during 
five  minutes,  at  the  end  of  which  he  destroyed 


40 


the  whole  of  the  cervical  part  of  the  spinal  mar- 
row ; he  renewed  the  artificial  inspiration  imme- 
diately after,  and  the  animal  remained  alive  as 
long  a time  as  it  was  judged  proper  to  continue 
the  artificial  respiration.  The  same  experiment 
was  repeated  with  the  same  result  on  two  other 
rabbits  of  the  same  age ; in  one  of  these,  five  mi- 
nutes after  having  destroyed  the  cervical  part  of 
the  spinal  marrow,  the  author  destroyed  about 
one-third  of  the  dorsal  part  of  the  spinal  marrow, 
then  five  minutes  after  a second  third,  and  the 
remaining  part  again  in  five  minutes.  The  cir- 
culation and  the  life  of  the  animal  continued  af- 
ter the  destruction  of  the  two  first  third  parts, 
and  only  ceased  after  that  of  the  last.  During 
the  whole  of  the  experiment  artificial  respiration 
had  only  been  interrupted  for  the  time  necessary 
for  the  destruction  of  the  spinal  marrow. 

These  experiments  led  M.  le  Gallois  to  that 
much  more  difficult  one,  the  object  of  which  is  to 
prove,  that  in  limiting  by  ligatures  the  circula- 
tion to  those  parts  which  correspond  to  any  par- 
ticular portion  of  the  spinal  marrow,  that  portion 
gives  to  the  heart  power  to  support  the  circula- 
tion in  those  parts.  He  separated  the  upper  and 
lower  from  the  central  parts  in  a rabbit  of  thirty 
days  old,  dividing  it  below  about  the  first  lum- 
bar vertebra,  and  above  about  the  second  cervi- 
cal vertebra,  then  by  artificial  respiration  he  sup- 
ported life  in  the  chest  thus  isolated.  We  do  not 


41 


describe  the  particulars  of  the  operation,  because 
the  author  has  detailed  them  in  his  memoir.  We 
shall  confine  ourselves  to  say,  that  the  experi- 
ment succeeded  perfectly,  although  an  artery, 
which  could  not  be  secured,  occasioned  a consi- 
derable hemorrhagy,  and  risked  the  success  of  the 
experiment. 

In  fine,  M.  le  Gallois  produced  partial  death 
in  the  hinder  parts  of  the  body  in  a rabbit  of 
about  twelve  days  old, ' by  tying  the  aorta  be- 
tween the  cseliac  and  anterior  mesenteric  arteries. 
At  the  end  of  twelve  minutes  the  death  of  the 
parts  appearing  complete,  he  untied  the  artery, 
and  life  by  degrees  appeared  in  the  whole  of 
these  parts,  so  that  the  animal  was  able  to  walk 
with  ease.  This  partial  resurrection  proved  that 
we  might  succeed  in  the  same  way  with  the  whole 
body,  if  it  were  possible  to  re-establish  the  circu- 
lation after  the  extinction  of  life  in  the  whole  of 
the  spinal  marrow ; but  the  experiments  of  the 
author  demonstrate  much  better  than  had  been 
done  before  him,  why  the  renewal  of  life  in  the 
whole  body  is  impossible. 

The  author  has  also  made,  in  our  presence, 
some  experiments  on  Guinea  pigs,  from  which  it 
appears,  that  in  these  animals  the  power  of  the 
heart  equally  depends  on  the  spinal  marrow, 
only  it  was  necessary  to  destroy  greater  portions 
of  it,  in  order  to  stop  the  circulation,  than  in  rab- 
bits of  the  same  age. 


8 


We  shall  finish  the  account  of  the  experiments 
which  M.  le  Gallois  repeated  in  our  presence,  by 
those  on  cold  blooded  animals,  the  results  of 
which  are  altogether  in  contradiction  to  those 
which  the  most  zealous  partizans  of  Haller,  and 
among  the  rest,  Fontana,*  have  obtained,  and 
which  have  been  so  much  valued.  The  author 
opened,  on  the  one  hand,  the  cranium,  and  on 
the  other,  the  chest  of  a frog,  and  brought  the 
heart  into  view ; he  then  fixed  the  animal  firmly, f 
and  while  one  of  us  observed  the  motions  of  the 
heart,  measuring  seconds  with  a watch,  he  de- 
stroyed the  brain  and  the  whole  of  the  spinal 
marrow  by  a stilet,  introduced  by  the  opening  in 
the  cranium  : in  an  instant  the  motions  of  the 
heart  stopped,  and  were  not  renewed  for  several 
seconds,  and  the  rate  of  their  repetition  never 
again  became  the  same  : they  were  more  frequent 
than  before  the  destruction  of  the  spinal  marrow. 
The  same  experiment  repeated  on  five  frogs  con- 
stantly gave  the  same  results ; the  motions  of  the 
heart  were  not  suspended  the  same  number  of  se- 
conds in  all,  but  the  suspension  was  always  very 
remarkable,  as  well  as  the  change  in  the  rate  of 
beating.  We  may  add,  that  the  amputation  of 

* Fontana.  Mem.  sur  les  parties  sensib.  et  irritab.  Tom. 
III.  p.  231.  Traite  sur  le  venin  de  la  vipere,  &c.  Florence, 
1781,  Tom.  II.  p.  169,  171. 

t Ibid.  p.  233  of  the  first  of  the  above  works,  and  171  of 
the  second. 


43 


the  thighs  of  frogs,  after  the  destruction  of  the 
spinal  marrow,  occasioned  no  hemorrhagy ; and 
salamanders,  decapitated  after  a similar  opera- 
tion, in  like  manner  lost  no  blood,  while  both  in 
the  one  case  and  the  other  there  had  been  he- 
morrhagy when  the  spinal  marrow  was  allowed 
to  remain  entire.  These  experiments  appear  to 
us  completely  to  confirm  all  the  inferences  which 
the  author  has  deduced  from  them,  and  with 
which  he  finishes  his  memoir.  To  confine  our- 
selves here  to  the  principal  points  we  shall  say, 
that  we  regard  as  demonstrated, 

1st.  That  the  cause  of  all  the  motions  of  inspi- 
ration has  its  seat  near  that  part  of  the  medulla 
oblongata  which  gives  rise  to  the  nerves  of  the 
eighth  pair. 

2d.  That  the  cause  which  animates  each  part 
of  the  body  resides  in  the  part  of  the  spinal  mar- 
row from  which  the  nerves  of  that  part  are  de- 
rived. 

3d.  That  in  like  manner  it  is  from  the  spinal 
marrow  that  the  heart  derives  its  life  and  its 
powers  ; but,  from  the  whole  spinal  marrow,  and 
not  merely  from  any  particular  part  of  it. 

4th.  That  the  great  sympathetic  nerve  takes 
its  rise  from  the  spinal  marrow,  and  that  the 
particular  character  of  that  nerve  is  to  bring  eve- 
ry part  to  which  it  is  distributed  under  the  im- 
mediate influence  of  the  whole  nervous  power. 

These  results  readily  explain  all  the  difficul- 


44 


ties  which  have  arisen  since  the  days  of  Haller 
respecting  the  causes  of  the  motions  of  the  heart. 
The  reader  will  recollect  that  the  principal  of 
these  are,  1st.  Why  does  the  heart  receive 
nerves  ? 2d.  Why  is  it  influenced  by  the  pas- 
sions? 3d.  Why  is  it  not  subjected  to  the  will? 
4th.  Why  does  the  circulation  continue  in  ace- 
phalus  and  decapitated  animals  ? He  will  recol- 
lect also,  that  till  nowr  no  explanation  has  been 
able  to  reconcile  these  points,  or  at  least  has  not 
been  able  to  do  so  without  the  aid  of  hypotheses 
which  we  have  seen  give  rise  to  other  difficulties. 
But  now  we  easily  conceive  why  the  heart  re- 
ceives nerves,  and  why  it  is  so  eminently  subject 
to  the  influence  of  the  passions,  because  it  is  ani- 
mated by  the  whole  of  the  spinal  marrow.  It 
does  not  obey  the  will,  because  none  of  the  or- 
gans which  are  under  the  influence  of  the  whole 
nervous  power  are  subject  to  it.  In  fine,  the  cir- 
culation continues  in  acephalus  and  decapitated 
animals,  because  the  motions  of  the  heart  do  not 
depend  on  the  brain,  or  only  depend  upon  it  in  a 
secondary  way.  We  ought  to  remark,  that  this 
last  point,  on  which  M.  le  Gallois  has  thrown  so 
much  light,  presents  only  confusion  and  errors  in 
authors  of  the  old  school  of  Haller,  as  well  as  in 
those  of  the  new  school.  None  of  them  have  dis- 
tinguished the  motions  of  the  heart  which  take 
place  after  decapitation,  from  those  which  we  ob- 
serve after  the  excision  of  this  organ,  or  after  the 


45 


destruction  of  the  spinal  marrow  ; and  they  have 
thought  that  both  were  equally  capable  of  main- 
taining the  circulation.  But  these  motions  differ 
essentially.  The  latter  have  no  power  to  sup- 
port the  circulation ; they  are  quite  similar  to  the 
feeble  movements  which  we  may  excite  in  the 
other  muscles  for  some  time  after  death.  M.  le 
Gallois  calls  them  motions  of  irritability,  without 
attaching  for  the  present  any  other  meaning  to  the 
term,  but  that  of  expressing  certain  phenomena 
after  death. 

We  have  still  one  task  to  perform,  to  point  out 
what  particularly  belongs  to  M.  le  Gallois  in  the 
work  which  is  the  object  of  this  report,  and  what 
others  are  entitled  to  claim. 

We  can  affirm  without  fear  of  contradiction, 
that  every  thing  in  this  work  belongs  to  him. — 
To  be  convinced  of  this,  it  is  only  necessary  to 
read  his  memoir  with  attention.  Chance  suggest- 
ed to  him  the  idea  of  his  first  experiment,  and 
that  experiment  led  him  to  all  the  others,  each  of 
them  being  suggested  to  him,  and  as  one  may 
say,  forced  upon  him  by  that  which  preceded  it. 
In  following  him  step  by  step,  one  observes 
that  his  own  method  has  been  his  only  guide, 
and  that  it  is  that  alone  which  has  inspired  him. 
Thus,  it  is  a thing  without  example  in  Physio- 
logy, to  see  a work  of  such  length,  in  which  all 
the  parts  are  so  connected,  so  dependent  on  each 
other,  that  to  have  the  complete  explanation  of 


46 


any  one  fact,  it  is  necessary  to  recur  to  all  those 
by  which  the  author  arrived  at  it,  and  in  which 
it  is  impossible  to  deny  one  inference  without  de- 
nying all  those  which  precede,  and  disturbing 
all  those  which  follow  it. 

One  might  have  expected  that  in  researches  so 
numerous,  and  which,  by  the  importance  of  the 
questions  they  embrace,  have  commanded  the  at- 
tention of  a great  number  of  philosophers,  the 
author  would  often  have  been  led,  even  in  con- 
fining himself  to  his  own  method,  to  repeat  ex- 
periments which  had  been  made  by  others ; yet 
among  all  the  experiments  found  in  his  memoir 
we  have  remarked  only  two  which  had  been 
made  before  him  ; one  by  Fontana,  the  other  by 
Stenon.  The  first*  consists  in  inflating  the  lungs 
and  thus  preserving  the  life  of  an  animal  after 
decapitation.  Fontana  only  made  that  experi- 
ment to  supply  oxygen  to  the  venous  blood ; and 
one  may  easily  perceive  that  he  was  a stranger 
to  the  object  before  us.  As  the  experiment  was  un- 
connected with  any  other  subject,  and  did  not 
serve  as  a proof  of  any  point  of  doctrine,  little 
attention  was  paid  to  it ; and  it  was  confounded 
with  many  other  facts,  shewing  that  even  warm 
blooded  animals  may  live  after  decapitation  with- 
out its  being  suspected  that  it  was  the  decapita- 

* Fontana.  Traite  sur  le  venin  de  la  vipere,  &c.  Tom.  I. 

p.  sir. 


47 

tion  which  enabled  them  to  live  in  that  state. — 
Hence  it  is  that  this  experiment  remained  almost 
unknown  except  in  some  of  the  Schools  of  Eng- 
land and  Germany ; and  M.  le  Gallois  was 
wholly  ignorant  of  it  when  he  communicated  to 
the  Society  of  Medicine  at  Paris  his  first  inqui- 
ries into  the  functions  of  the  spinal  marrow.  Be- 
sides, this  experiment  in  the  hands  of  M.  le  Gallois 
was  only  one  of  the  means  by  which  he  demon- 
strated two  of  his  principal  discoveries,  namely, 
that  the  cause  of  the  motions  of  inspiration  has  its 
seat  in  the  medulla  oblongata,  and  that  the  cause 
of  life  in  the  trunk  resides  in  the  spinal  marrow. 

The  experiment  of  S tenon  is  that  in  which  the 
ventral  aorta  is  tied  and  then  untied,  to  shew  that 
the  interruption  of  the  circulation  in  any  part  oc- 
casions paralysis  of  that  part,  and  that  the  return 
of  the  blood  restores  life  to  it.  This  experiment 
is  well  known,  and  has  often  been  repeated.  Some 
of  the  authors  who  have  made  it,  had  in  view  to 
prove  that  the  contractions  of  the  muscles  depend 
on  the  action  of  the  blood  on  their  fibres ; others 
that  the  sensibility  of  every  part  depends  on  the 
circulation ; and  in  both  views  it  served  equally  to 
prove  or  disprove  the  point,  according  to  the 
manner  in  which  it  was  made.  Thus,  when  they 
secured  the  ventral  aorta,  the  feeling  and  motion 
of  the  lower  parts  of  the  body  quickly  ceased.* 

* Lorry,  Journal  de  Med.  An.  1757,  p.  15.  Haller,  Mem. 
sur  le  Mouvement  du  Sang,  p.  203,  Exp.  52. 


48 


But  when  the  ligature  was  made  lower,  and  only 
on  one  of  the  crural  arteries,  although  in  this  case 
the  circulation  was  wholly  interrupted  in  the  cor- 
responding member,  feeling  and  motion  conti- 
nued in  it  for  a long  time.*  In  these  opposite 
results  each  author  did  not  fail  to  adopt  those 
which  favoured  his  own  opinion,  and  he  thought 
himself  authorised  to  do  so,  as  the  real  cause  of 
the  difference  was  unknown. 

In  the  hands  of  M.  le  Grallois  the  same  expe- 
riment shews  itself  under  a very  different  aspect, 
and  assumes  a determined  meaning.  It  is  evi- 
dent that  feeling  and  motion  ceasing  in  the  hinder 
parts  from  a ligature  being  thrown  round  the 
aorta,  arises  from  its  being  only  in  this  case  that 
the  circulation  is  interrupted  in  that  portion  of 
the  spinal  marrow  which  gives  rise  to  the  nerves 
of  these  parts.  Such  are  the  only  experiments  of 
M.  le  Gallois,  as  far  as  we  know,  which  can  be 
claimed  by  others  ; but  besides  that  the  manner 
in  which  they  make  a part  of  his  work  renders 
them  his  own,  it  appears  to  us  that  the  newr  points 
of  view,  under  which  he  presents  them,  and  the 
precision  of  the  details  and  clearness  of  the  re- 
sults which  he  has  substituted  for  the  uncertainty 
and  obscurity  in  which  they  w ere  formerly  in- 
volved, have  made  them  experiments  w holly  newr. 

* Schwenke,  Hcematol.  p.  8.  The  57th  and  58th  Experi- 
ments of  Haller,  p.  205,  are  of  the  same  kind. 


49 


We  shall  finish  by  a few  words  on  an  opinion 
of  M.  Prochaska,  which  may  be  believed  to  be 
similar  to  that,  which  M.  le  Grallois  has  demon- 
strated respecting  the  functions  of  the  spinal  mar- 
row. That  author  places  the  sensorium  com- 
mune in  the  brain  and  spinal  marrow  conjoint- 
ly.* * * § But  it  is  necessary  to  be  aware  that  he 
thinks  that  the  nervous  power  is  generated 
throughout  the  whole  extent  of  the  nervous  sys- 
tem, so  that  every  part  derives  from  its  own 
nerves,  taken  alone,  the  cause  of  its  life  and  of  its 
movements.!  He  only  regards  the  sensorium  as 
a central  point,  where  the  nerves  of  feeling  as 
well  as  those  of  motion  meet  and  communicate, 
and  which  establishes  the  connection  between  the 
different  parts  of  the  body.J  On  the  contrary, 
M.  le  Grallois  has  demonstrated  that  the  spinal 
marrow  is  not  merely  a means  of  communication 
between  different  parts,  but  that  from  it  the  cause 
of  the  life  and  power  of  the  whole  body  proceeds. 
And  what  proves  that  M.  Procliaska,  in  announ- 
cing his  opinion,  which  besides  he  only  mentions 
as  a thing  probable,  §>  was  far  from  suspecting  the 
true  functions  of  the  spinal  marrow,  is,  that  he 

* Opera  Minor.  Tom.  II.  p.  51.  Before  him  Marherr. 
Hartley,  &c.  had  been  of  the  same  opinion, 

t Opera  Minor.  Tom.  II.  p.  82. 

$ lb.  p.  151. 

§ lb.  p.  153. 


9 


50 


regards  it  as  only  a great  bundle  of  nerves,  eras - 
sus  funis  nerveus.* 

In  a word,  it  appears  to  us  that  we  may  say 
of  the  authors  who  have  had  some  views  on  the 
subjects  of  which  M.  le  Gallois  treats,  what  M. 
Laplace  has  said  with  so  much  justice  on  a simi- 
lar occasion.  One  may  there  meet  with  some 
truths,  but  they  are  almost  always  mixed  with  so 
many  errors  that  their  discovery  belongs  only  to 
him,  who,  separating  them  from  this  mixture, 
succeeds  by  calculation  or  observation  in  effec- 
tually establishing  them.f 

The  opinion  of  your  Committee  is,  that  the 
work  of  M.  le  G allois  is  one  of  the  most  excellent 
and  certainly  the  most  important  which  has  ap- 
peared in  Physiology  since  the  learned  experi- 
ments of  Haller ; that  this  work  will  make  an 
epoch  in  that  science  over  which  it  must  spread  a 
new  light;  that  its  author,  so  modest,  so  labo- 
rious, so  meritorious,  deserves  that  the  class  be- 
stow on  him  its  especial  commendation,  and  all 
the  encouragement  which  it  can  give.  They  can- 
not help  adding,  that  the  memoir  of  which  they 
have  given  an  account  is  worthy  to  occupy  a dis- 
tinguished place  in  the  Transactions  of  learned 
correspondents,  if  the  publicity  of  the  important 

* lb.  p.  48. 

t Mem.  sur  l’Adhesion  ties  Corps  a la  Surface  des  Fluides 
dans  la  Biblioth.  Britan.  Tom.  XXXIV.  p.  35. 


51 


discoveries  contained  in  it  may  be  deferred  to  the 
time,  perhaps  distant,  of  the  publication  of  those 
Transactions. 

(Signed)  DE  HUMBOLDT. 

HALLE. 

PERCY. 

The  Class  approve  their  Report  and  adopt  its 
conclusions. 

It  moreover  decrees,  that  the  Report  shall  be 
printed  in  the  History  of  the  Class,  and  that  the 
Committee  of  the  Class  shall  make  arrangements 
with  M.  le  Grallois  for  defraying  the  expenses 
which  have  been  occasioned  by  his  experiments, 
and  enabling  him  to  continue  them. 

Certified  to  be  conformable  to  the  original. 

G.  CUVIER, 
Perpetual  Secretary. 


CHAP.  II. 


Observations  on  the  foregoing  Report. 

Ijt  will  be  necessary  before  I enter  on  the  ac- 
count of  my  experiments  to  make  some  observa- 
tions on  the  foregoing  report.  As  an  account  of 
the  state  of  our  knowledge  of  the  subject  at  the 
time  M.  le  Grallois  began  his  experiments,  it  ap- 


cK 


52 


pears  to  be  accurate,  well  arranged,  and  suffici- 
ently comprehensive.  As  an  account  of  the  expe- 
riments and  opinions  of  this  author,  nothing,  as 
far  as  I can  judge,  can  be  more  clear  and  cor- 
rect ; as  an  estimate  of  the  merits  of  his  work  it 
does  not  seem  to  me  to  deserve  the  same  praise. 
It  overlooks  defects,  both  in  his  experiments  and 
reasonings,  of  such  moment,  as  wholly  to  invali- 
date all  his  most  important  conclusions ; and  to 
leave  him  the  discoverer  of  certain  unconnected 
though  most  valuable  facts,  instead  of  the  author 
of  a new  system,  founded,  as  the  report  alledges* 
on  a basis  never  to  be  shaken. 

M.  le  Gallois  has  demonstrated,  that  the  sud- 
den destruction  of  any  considerable  portion  of  the 
spinal  marrow  so  enfeebles  the  power  of  the 
heart,  that  it  is  no  longer  capable  of  supporting 
the  circulation.  He  has  also  shewn  that  the 
same  portion  of  the  spinal  marrow,  whose  sud- 
den destruction  destroys  the  circulation,  may  be 
destroyed  by  small  parts  without  materially  af- 
fecting it.  The  question  then  arises,  if,  as  M.  le 
Gallois  supposes,  the  power  of  the  heart  is  deriv- 
ed from  the  spinal  marrow,  and  necessarily  ceases 
when  any  considerable  part  of  the  spinal  mar- 
row can  no  longer  perform  its  functions,  why  does 
the  particular  mode  of  destroying  it  make  so 
great  a difference  in  the  result  ? This  difficulty 
occasioned  so  much  trouble  to  M.  le  Gallois,  that 
it  had  nearly  induced  him  to  abandon  the  inquiry 


53 


u Apres  bien  des  efforts  inutiles  pour  porter  la 
lumiere  dans  cette  tenebreuse  question,  je  pris 
le  parti  de  1’  abandonner,  non  sans  regret  d’y 
avoir  sacrifie  un  grand  nombre  d’animaux,  et 
perdu  beaucoup  de  temps.”  Just  before,  he  ob- 
serves, <(  En  un  mot,  j?eus  presque  autant  de  re- 
sultats  differens  que  d’experiences.”  And  in- 
deed the  apparent  contradictions  in  the  results  of 
M.  le  Gfallois’  experiments  are  such,  as  at  first 
view  to  have  persuaded  me  that  some  of  his  ex- 

• • i- 

periments  were  inaccurate  ; on  repeating  many 
of  them,  however,  I was  convinced  of  their  ac- 
curacy. He  attempts,  we  have  seen,  to  explain 
the  difficulty  in  the  following  manner.  He  has 
shewn  that  if  ligatures  be  thrown  round  the  large 
vessels,  at  no  great  distance  from  the  heart,  so  as 
greatly  to  lessen  the  extent  of  the  circulation,  this 
organ  can  still  support  it,  notwithstanding  the 
destruction  of  such  a portion  of  the  spinal  mar- 
row as  would,  under  ordinary  circumstances, 
have  destroyed  it.  On  the  same  principle  ac- 
couchetirs  apply  tourniquets  to  the  limbs  in  cases 
of  profuse  uterine  liemorrhagy.  Now  M.  le 
Gallois  supposes,  that  the  power  of  the  blood- 
vessels, as  well  as  that  of  the  heart,  depending 
on  the  spinal  marrow,  we  greatly  impair  the  vi- 
gour of  the  circulation  in  any  part  by  destroying 
that  portion  of  the  spinal  marrow  by  which  its 
nervous  influence  is  supplied ; and,  therefore, 
that  when  any  portion  of  the  spinal  marrow  is 


destroyed  by  small  parts,  the  vigour  of  the  cir- 
culation in  the  corresponding  parts  of  the  body 
being  greatly  impaired,  nearly  the  same  etfect  is 
produced  as  if  ligatures  had  been  thrown  round 
their  vessels.  It  might  here  be  objected,  that 
when  a considerable  portion  of  the  spinal  marrow 
is  at  once  destroyed,  the  power  of  the  vessels  cor- 
responding to  this  portion  being  lost,  the  effect 
produced  by  the  ligatures  should  still  be  observ- 
ed. To  this  I suppose  M.  le  Gallois  would 
have  replied,  that  as  it  requires  some  time  for  the 
destruction  of  any  part  of  the  spinal  marrow  to 
produce  its  effect  on  the  vessels,  when  a large 
portion  is  destroyed  at  once,  the  vessels  not  ac- 
commodating themselves  to  the  rapid  destruction 
of  the  successive  parts  of  the  spinal  marrow,  the 
circulation  is  lost. 

The  foregoing  explanation  resting  wholly  on 
the  position,  that  the  vessels  of  any  part  are  de- 
bilitated when  deprived  of  the  influence  of  the 
corresponding  part  of  the  spinal  marrow,  it  was 
incumbent  on  the  Committee  to  inquire  by  what 
experiments  M.  le  Gallois  had  established  it. 
This  question,  however,  is  w holly  overlooked  by 
them ; and,  on  review  ing  the  experiments  of  M.  le 
Gallois,  we  find  none  from  which  any  such  infer- 
ence can  be  drawn.  He  attempts  to  support  it 
only  by  experiments  not  properly  bearing  on  the 
point ; although,  if  the  position  be  correct,  the 
simplest  experiments  are  sufficient  to  establish  it. 


55 


It  is  impossible  from  his  experiments  to  say, 
whether  the  diminished  circulation  in  the  parts  in 
question  arose  directly  from  the  destruction  of 
part  of  the  spinal  marrow,  or  from  the  lessened 
power  of  the  heart. 

Another  error  of  even  greater  consequence  than 
the  foregoing  in  the  reasonings  of  M.  le  Gallois, 
which  is  also  overlooked  by  the  Committee,  is 
his  inference  that  the  spinal  marrow  possesses  an 
influence  over  the  heart  not  possessed  by  the 
brain  ; because  he  found  that  removing  the  brain 
produces  little  or  no  effect  on  the  action  of  the 
heart,  while  crushing  the  whole,  or  a considera- 
ble part  of  the  spinal  marrow,  greatly  enfeebles 
it.  But  to  obtain  this  inference,  it  is  evident  that 
the  brain  and  spinal  marrow  must  be  subjected 
to  the  same  power.  They  ought  both  to  have 
been  removed  or  both  crushed. 

The  inferences  which  M.  le  Gallois  makes 
from  the  effects  of  crushing  the  spinal  marrow  are 
in  another  respect  incorrect.  There  are  two 
ways  in  which  we  may  account  for  the  power  of 
the  heart,  or  of  the  blood-vessels,  being  destroy- 
ed by  crushing  the  spinal  marrow.  Either  the 
heart  and  blood-vessels  derive  their  power  from 
the  spinal  marrowy  and  consequently  lose  it  on 
the  destruction  of  the  whole  or  a considerable 
part  of  that  organ  ; or,  deriving  their  power  from 
some  other  source,  they  are  influenced  by  agents 
acting  on  the  spinal  marrow.  It  was  incumbent 


56 


on  M.  le  Gallois,  therefore,  to  ascertain  by  ex- 
periment in  which  of  these  wajs  crushing  the 
spinal  marrow  produces  the  effects  he  observed. 
But  he  does  not  even  seem  aware,  that  it  may 
act  in  any  other  way  than  that  which  he  sup- 
poses. 

The  inference  which  he  draws  from  the  resto- 
ration to  life  of  the  lower  parts  of  an  animal 
when  a ligature,  which  has  been  thrown  round 
the  abdominal  aorta,  is  removed,  is  inadmissible, 
namely,  that  when  the  circulation  in  every  part 
is  destroyed  by  crushing  the  spinal  marrow,  and 
we  find  that  we  cannot  by  any  means  restore  it, 
this  is  to  be  ascribed  to  the  absence  of  the  influ- 
ence of  the  spinal  marrow.  The  same  result 
may  arise,  it  is  evident,  from  the  heart  and  blood- 
vessels, supposing  them  to  derive  their  power 
from  some  other  source,  being  so  deranged  by  a 
powerful  agent  acting  through  the  spinal  marrow, 
that  they  are  no  longer  capable  of  performing 
their  functions.  M.  le  Gallois  relates  no  experi- 
ment to  prove  that  his  explanation  ought  to  be 
admitted  in  preference  to  this ; and  the  Commit- 
tee speak  as  if  no  inference,  but  that  of  M.  le 
Gallois,  could  be  drawn  from  the  experiment. 

Nor  is  M.  le  Gallois’  inference  respecting  the 
origin  of  the  great  sympathetic  nerve  warranted 
by  his  experiments ; namely,  that  it  arises  wholly 
from  the  spinal  marrow.  It  is  true  that  he  has 
found,  that  through  this  nerve  a powerful  agent. 


o7 


applied  to  any  considerable  portion  of  the  spinal 
marrow,  is  capable  of  enfeebling  the  power  of  the 
heart ; but  nothing  said  by  M.  le  Gallois  proves 
that  this  is  not  also  true  of  the  brain. 

A position  on  which  much  of  the  reasonings  of 
M.  le  Gallois  rests,  which  is  admitted  by  the 
Committee,  but  of  which  we  find  no  proof  in  the 
experiments  of  this  author,  is,  that  the  contrac- 
tions of  the  heart,  after  it  is  removed  from  the 
body,  are  of  a nature  different  from  those  which 
support  the  circulation.  Observing  that  after  the 
spinal  marrow  is  crushed,  the  contractions  of  the 
heart  are  too  feeble  to  support  the  circulation ; 
without  further  inquiry  he  concludes,  that  these 
contractions  do  not  merely  differ  in  degree  from 
those  which  support  the  circulation,  but,  existing 
independently  of  the  spinal  marrow,  are  wholly 
of  a different  nature.  The  contractions  of  the 
heart,  after  it  is  removed  from  the  body,  are  re- 
garded  by  M.  le  Gallois  as  analogous  to  those 
which  remain  after  the  spinal  marrow  is  crushed, 
and  he  regards  in  the  same  light  the  contractions 
which  may  be  excited  for  a short  time  after  death 
in  the  muscles  of  voluntary  motion.  Had  M.  le 
Gallois’  mind  been  unbiassed  by  his  peculiar 
views  of  the  subject,  he  would  have  easily  ob- 
served a striking  difference  between  the  action  of 
the  heart,  immediately  after  the  spinal  marrow  is 
crushed,  and  its  action  immediately  after  it  is  re- 
moved from  the  body.  In  the  former  instance,  it 

40 


58 


is  feeble  and  fluttering,  gradually  becoming  ra 
ther  stronger  and  more  regular  ; in  the  latter  in- 
stance, it  is  comparatively  strong  and  regular, 
gradually,  and  in  the  cold  blooded  animal  very 
slowly,  becoming  more  feeble.  With  respect  to 
the  contractions  of  the  muscles  of  voluntary  mo- 
tion after  death,  it  is  generally  known  that  these 
muscles  may  for  some  time  be  excited  to  the  per- 
fect performance  of  their  function.  They  can  be 
made  to  move  the  limbs  precisely  as  they  did  be- 
fore the  death  of  the  animal.  But  whether  they 
move  them  as  forcibly  or  not,  and  whether  or  not 
the  heart  beats  as  forcibly  after  it  is  removed  from 
the  body,  as  while  it  supported  the  circulation,  as 
far  as  we  can  see,  the  action  of  both  is  of  the 
same  nature  as  when  they  performed  their  usual 
functions;  and  M.  le  Gallois  has  adduced  no 
proof  whatever  of  its  being  of  a different  nature. 
The  experiment,  indeed,  in  which  he  lessens  the 
extent  of  the  circulation  by  ligatures,  and  thus  en- 
ables the  heart  to  support  it  after  such  a portion  of 
the  spinal  marrow  is  destroyed,  as  would  other- 
wise have  destroyed  it,  is  a sufficient  refutation  of 
his  own  opinion.  It  proves  that  the  effect  of 
crushing  a large  portion  of  the  spinal  marrow  is 
merely  that  of  enfeebling,  not  changing  the  nature 
of  the  action  of  the  heart. 

Another  position  of  M.  le  Gallois  admitted  by 
the  Committee  which  does  not  seem  to  be  war- 
ranted by  his  experiments  is,  that  the  power,  on 


59 


which  all  the  motions  of  inspiration  depend,  has 
its  seat  near  that  part  of  the  medulla  oblongata, 
which  gives  rise  to  the  eighth  pair  of  nerves.  On 
this  subject  I shall  hereafter  have  occasion  to 
make  many  observations ; and  shall  only  observe 
here  that  inspiration  is  a complicated  func- 
tion ; and  that  if  any  of  the  powers  essential 
to  it  is  withdrawn,  its  most  essential  motions  are 
as  quickly  destroyed  as  if  all  these  powers  had 
ceased.  Now  M.  le  Gallois  made  no  experi- 
ments to  ascertain  whether  it  is  by  the  destruction 
of  one  or  all  of  these  powers,  that  inspiration  is 
destroyed  by  destroying  this  part  of  the  medulla 
oblongata. 

The  argument  employed  by  the  Committee  in 
favour  of  M.  le  Gallois’  opinions  from  the  exist- 
ence of  acephalous  foetuses,  is  wholly  invalidated 
by  the  fact,  that  foetuses  have  been  born  alive 
without  either  brain  or  spinal  marrow ; for  in- 
stances of  which  M.  le  Gallois  himself  refers  in 
the  two  hundred  and  fifty-first  page  of  his  Trea- 
tise to  the  Hist,  de  VAcad.  des  Sciences  An. 
1711?  Ohs.  Anat.  3,  and  An.  1713,  Obs.  Anat. 
6,  but  without  attempting  to  shew  how  it  is  pos- 
sible to  reconcile  his  opinions  with  the  existence 
of  such  cases. 

An  inconsistency  of  great  importance  in  M.  le 
Gallois’  work,  which  he  makes  no  attempt  to 
explain,  is  overlooked  by  the  Committee.  He 
observes,  in  the  commencement  of  his  work, 


60 


{{ Ce  que  j’y  ai  dit  du  Cceur  pouvant  s’appliquer 
aux  autres  organes  des  fonctions  involuntaires, 
la  question  peut  etre  consideree  plus  generale- 
ment,  comme  la  determination  du  siege  du  prin- 
cipe  qui  preside  a cet  ordre  de  fonctions.’**  Yet 
lie  shews  that  decapitation  does  not  influence  the 
function  of  the  heart,  while  the  division  of  the 
eighth  pair  of  nerves  injures  that  both  of  the 
lungsf  and  stomach. 

It  appears  from  what  has  been  said,  as  far  as 
I am  capable  of  judging,  that  the  experiments  of 
M.  le  Grallois  do  not  warrant  any  of  the  follow- 
ing positions  stated  by  the  Committee  as  the  re- 
sult of  his  experiments. 

(e  1°  Que  le  principe  de  tous  les  mouvemens  in- 
spiratoires  a son  siege  vers  cet  endroit  de  la 
moelle  allongee  qui  donne  naissance  aux  nerfs  de 
la  huitieme  paire ; 

“ 3°  Que  le  principe  qui  anime  chaque  partie 
du  corps  reside  dans  ce  lieu  de  la  moelle  epiniere 
duquel  naissent  les  nerfs  de  cette  partie; 

u 3°  Que  c’est  pareillement  dans  la  moelle  epi- 
niere que  le  cceur  puise  le  principe  de  sa  vie  et 
de  ses  forces ; mais  dans  cette  moelle  toute  entiere, 
et  non  pas  seulement  dans  une  portion  circon- 
scrite ; 

“ 4°  Que  le  grand  sympatliique  prend  nais- 

* Avant-propos.  page  1. 

t I speak  here  of  the  functions  of  the  lungs  themselves, 
not  of  the  muscles  of  inspiration-. 


61 


stance  dans  la  moelle  epiniere,  et  que  le  carac- 
tere  particulier  de  ce  nerf  est  de  mettre  chacune 
des  parties,  auxquelles  il  se  distribue  sous  l’influ- 
ence  immediate  de  toute  la  puissance  nerveuse 
that  is  of  the  whole  of  the  spinal  marrow,  which 
M.  le  Gallois  regards  as  the  seat  of  the  nervous 
influence. 

If  these  results  are  not  legitimate  inferences 
from  the  experiments  of  M.  le  Gallois,  the  expla- 
nations of  the  long  contested  points  respecting  the 
action  of  the  heart,  founded  on  them,  are  inadmis- 
sible ; namely,  That  the  heart  is  supplied  with 
nerves  because  it  derives  its  power  from  the  spi- 
nal marrow ; That  it  is  influenced  by  the  pas- 
sions, because  the  brain  acts  upon  it  through  the 
spinal  marrow ; That  it  does  not  obey  the  will, 
because  no  organ  influenced  by  every  part  of  the 
nervous  power,  that  is  of  the  spinal  marrow,  does 
obey  the  will ; (it  may  here  be  remarked,  that 
were  this  position  admitted,  it  would  by  no  means 
explain  why  the  motions  of  the  heart  are  inde- 
pendent of  the  will,  though  influenced  by  the  pas- 
sions,) and,  That  the  circulation  continues  in 
acephalous  and  decapitated  animals,  because  its 
direct  dependence  is  not  on  the  brain,  but  on  the 
spinal  marrow. 

If  the  foregoing  observations  are  correct,  we 
must  dissent  from  the  following  opinion  of  the 
Committee.  “ Ces  resultats  resolvent  sans  peine 
toutes  les  difflcultes  qui  se  sont  elevees  depuis 


62 


Haller  sur  les  causes  des  mouvements  du  coeur.” 
The  experiments  of  M.  le  Gallois  indeed,  by  as- 
certaining some  facts  of  great  importance,  while 
others  immediately  connected  with  them  escaped 
his  observation,  have  left  the  subject  in  greater 
confusion  than  he  found  it.  Instead  of  removing 
the  difficulties  which  formerly  existed,  the  valu- 
able additions  which  he  has  made  to  our  know- 
ledge have  shewn  us  others. 

The  heart’s  being  subject  to  the  passions,  yet 
independent  of  the  influence  of  the  brain,  on 
which  so  much  has  been  written,  does  not  seem 
to  imply  a more  direct  contradiction,  than  that 
the  destruction  of  the  same  part  of  the  spinal  mar- 
row should,  according  to  the  way  in  which  it  is 
effected,  either  destroy  the  function  of  the  heart, 
or  little,  if  at  all,  influence  it.  I have  had  occa- 
sion to  observe  that  M.  le  Gallois’  explanation  of 
this  apparent  contradiction  is  not  a legitimate  in- 
ference from  his  experiments  ; and  I shall  soon 
relate  some,  so  simple  that  it  is  impossible  to  be 
deceived  in  their  result,  which  seem  directly  to  re- 
fute that  explanation. 

Why,  if  the  power  of  the  heart  depends  on  the 
spinal  marrow,  as  it  appears  to  do  from  the  ex- 
periments of  M.  le  Gallois,  the  accuracy  of  which 
I have  ascertained  by  repeated  trials,  have  foetuses 
been  born  alive  where  no  spinal  marrow  had  ever 
existed? 

Why,  if  the  power  of  the  heart  depends  on  the 


63 


spinal  marrow,  does  it  continue  to  perform  its 
usual  motions  after  it  is  removed  from  the  body  ? 

Why,  if  (as  M.  le  Gallois  maintains,  and  it  is 
generally  admitted,)  the  various  organs  of  invo- 
luntary motion  bear  the  same  relation  to  the  ner- 
vous system,  is  the  function  of  the  heart  uninflu- 
enced by  decapitation,  and  that  of  the  stomach 
immediately  impaired  by  dividing  or  throwing  a 
ligature  round  the  eighth  pair  of  nerves  ? 

Why  does  respiration  cease  on  the  destruction 
of  a certain  part  of  the  medulla  oblongata,  since 
the  nerves  of  the  diaphragm  and  intercostal  mus- 
cles arise  from  the  spinal  marrow,  which  M.  le 
Gallois  has  proved  to  be  capable  of  exciting  the 
muscles  independently  of  the  brain?  He  consi- 
ders this  subject  at  length  in  the  thirty -fifth  and 
following  pages  of  his  treatise,  and  admits  that 
he  can  give  no  explanation  of  it,  calling  it  “ one 
of  the  great  mysteries  of  the  nervous  power,  the 
discovery  of  which  will  throw  the  strongest  light 
on  the  mechanism  of  the  functions  of  that  wonder- 
ful power.” 

These  apparent  contradictions,  it  is  evident,  as 

well  as  those  which  existed  before  the  discoveries 

/ 

of  M.  le  Gallois,  must  he  reconciled  before  we 
can  be  said  to  understand  the  relation  which  the 
thoracic  and  abdominal  viscera  bear  to  the  ner- 
vous system.  The  doctrine  which  cannot  recon- 
cile them  must  be  erroneous. 


PART  II. 


Experiments  made  with  a view  to  ascertain  the 
laws  of  the  vital  functions. 

The  sanguiferous  system,  it  is  evident,  may 
be  divided  into  three  parts,  whose  functions  dif- 
fer ; the  heart,  the  vessels  of  circulation,  and  the 
vessels  of  secretion.  In  the  following  Inquiry  I 
shall,  in  the  first  place,  endeavour  to  ascertain  the 
principle  on  which  the  action  of  the  heart  and  the 
vessels  of  circulation  depends,  and  the  relation 
which  subsists  between  them  and  the  nervous 
system.  I shall  then  cousider  the  principle  on 
which  the  action  of  the  muscles  of  voluntary  mo- 
tion depends,  and  the  relation  which  they  bear  to 
this  system.  The  comparative  effects  of  stimuli, 
applied  to  the  brain  and  spinal  marrow,  on  the 
heart  and  muscles  of  voluntary  motion,  will  next 
be  considered.  An  account  of  the  experiments  on 
these  branches  of  the  subject,  though  not  in  the 
order  in  which  they  are  here  related,*  was  pre- 
sented to  the  Royal  Society  in  two  papers,  com- 
posed while  I was  still  engaged  in  the  Inquiry, 


* The  experiments  which  I have  since  made  have  led  to 
conclusions  which  render  a different  arrangement  neces- 
sary. 


65 

and  published  in  the  Philosophical  Transactions 
of  1815. 

The  next  object  of  inquiry  will  be  the  principle 
on  which  the  action  of  the  secreting  vessels  de- 
pends, and  the  relation  which  they  bear  to  the 
nervous  system.  I shall  then  endeavour  to  ascer- 
tain the  principle  on  which  the  action  of  the  ali- 
mentary canal  depends,  and  the  relation  which  it 
bears  to  this  system.  These  subjects  will  lead  to 
some  experiments  and  observations  on  the  use  of 
the  ganglions,  the  nature  of  the  nervous  influ- 
ence, and  the  cause  of  animal  temperature.  I 
shall  then  consider  the  relation  which  the  differ- 
ent functions  of  the  animal  body  bear  to  each 
other,  and  the  order  in  which  they  cease  in  dy- 
ing ; and  the  Inquiry  will  conclude  with  a review 
of  the  inferences  obtained  from  the  various  expe- 
riments and  observations  which  will  be  laid  be- 
fore the  reader,  and  some  remarks  on  their  appli- 
cation to  explain  the  nature  and  improve  the  treat- 
ment of  diseases. 


11 


i 


66 


CHAP.  I. 

On  the  'principle  on  which  the  action  of  the  heart 
and  vessels  of  circulation  depends. 

As  it  is  now  generally  admitted  by  Physiolo- 
gists, as  appears  from  the  report  just  laid  before 
the  reader,  that  the  heart  is  capable  of  perform- 
ing its  functions  after  the  brain  is  removed,  the 
first  question  which  presents  itself  is,  how  far 
does  the  power  of  this  organ  depend  on  the  influ- 
ence of  the  spinal  marrow,  from  which,  we  have 
seen,  M.  le  Gtallois  maintains,  that  it  is  wholly 
derived. 

Exp.  1.  A rabbit  was  deprived  of  sensation 
and  voluntary  power  by  a blow  on  the  occiput. 
When  the  rabbit  is  killed  in  this  way,  the  respi- 
ration immediately  ceases : but  the  action  of  the 
heart  and  the  circulation  continue,  and  may  be 
supported  for  a considerable  length  of  time  by  ar- 
tificial respiration,  as  practised  by  Fontana,  and 
since  by  Chirac,  Mr.  Brodie,  M.  le  (xallois,  and 
others.*  This  mode  of  destroying  the  sensibility 

* It  appears  from  the  first  volume  of  the  Philosophical 
Transactions,  that  Mr.  Hook,  in  the  year  l66r,  shewed  in 
the  presence  of  the  Members  of  the  Royal  Society,  not  only 
that  the  life  of  a dog  could  be  preserved  for  an  hour  after 
the  thorax  had  been  opened,  and  a great  part  of  the  dia- 
phragm removed,  by  alternately  inflating  the  lungs  and  al- 


67 


does  not  influence  the  result  of  the  experiment, 
and  has  the  double  advantage  of  preventing  the 
animaPs  sufferings,  and  his  motions.  Its  greatest 
inconvenience  is,  that  if  the  blow  is  very  severe, 
considerable  vessels  are  sometimes  ruptured,  and 
there  is  almost  always  some  rupture  of  vessels, 
which  of  course  tends  to  impair  the  vigour  of  the 
circulation. 

In  the  present  experiment,  the  circulation  was 
supported  by  artificial  respiration.  The  spinal 
marrow  was  laid  bare  from  the  occiput  to  the  be- 
ginning of  the  dorsal  vertebrae.  The  chest  was 
then  opened,  and  the  heart  found  beating  regular- 
ly, and  with  considerable  force.  The  spinal  mar- 
row, as  far  as  it  had  been  laid  bare,  was  now 
wholly  removed,  but  without  in  the  least  affect- 
ing the  action  of  the  heart.  After  this,,  the  artifi- 
cial respiration  being  frequently  discontinued,  we 
repeatedly  saw  the  action  of  the  heart  become 
languid,  and  increase  on  renewing  it.  The  skull 
was  then  opened,  and  the  whole  brain  removed, 
so  that  no  part  of  the  nervous  system  remained 
above  the  dorsal  vertebrae,  but  without  any  abate- 
ment of  the  action  of  the  heart,  which  still  conti- 
nued to  be  more  or  less  powerful,  according  as 

lowing  them  to  collapse  so  as  to  imitate  respiration ; but 
that  the  effect  is  nearly  the  same  if  the  lungs  are  preserved 
in  a state  of  permanent  distension,  by  air  constantly  thrown 
into  them,  and  allowed  to  escape  by  small  perforations  made 
in  their  surface. 


68 


we  discontinued  or  renewed  artificial  respiration. 
This  being  for  a considerable  time  discontinued, 
the  ventricles  ceased  to  beat  about  half  an  hour 
after  the  removal  of  the  brain.  On  renewing  the 
respiration,  however,  the  action  of  the  ventricles 
was  restored.  The  respiration  was  again  discon- 
tinued and  renewed,  with  the  same  effects. 

Exp.  2.  A rabbit  was  made  insensible  by  re- 
moving part  of  the  skull,  and  applying  opium  to 
the  brain.  The  spine  was  then  opened  between 
the  cervical  and  dorsal  vertebra.  We  then  laid 
open  the  thorax,  and  supported  the  action  of  the 
heart  by  artificial  respiration.  The  force  with 
which  it  beat  was  carefully  observed,  and  the 
spinal  marrow  destroyed  by  running  a small  hot 
wire  up  and  down  the  spine,  through  the  open- 
ing made  .in  it,  by  which  the  action  of  the  heart 
was  not  at  all  affected. 

Exp.  3.  In  the  foregoing  experiments,  it  may 
he  said,  there  was  no  direct  proof  of  the  continu- 
ance of  the  circulation  after  the  spinal  marrow 
was  destroyed  or  removed.  On  this  account  se- 
veral of  the  following  experiments  were  made. 
A rabbit  was  deprived  of  sensation  by  a blow  on 
the  occiput,  and  the  circulation  supported  by  arti- 
ficial breathing.  The  carotids  being  exposed 
were  seen  beating.  The  cervical  part  of  the  spi- 
nal marrow  was  then  destroyed  by  a hot  wire, 
after  which  the  carotids  were  still  found  perfect- 
ly round  and  beating. 


69 


Exp.  4.  In  a rabbit  rendered  insensible  by  a 
blow  on  the  occiput,  the  whole  spinal  marrow 
was  destroyed  by  a hot  wire,  and  the  breathing 
artificially  supported.  One  of  the  carotid  arte- 
ries was  then  laid  bare.  Its  beating  was  evident, 
and  on  dividing  it,  florid  blood  flowed  from  it 
freely. 

Exp.  5.  The  only  difference  between  this  and 
the  last  experiment  was,  that  artificial  breathing 
was  not  performed.  In  both,  the  spinal  marrow 
was  destroyed,  by  introducing  a wire  hot  enough 
to  make  a hissing  noise  through  an  opening  be- 
tween the  cervical  and  dorsal  vertebrae,  first 
through  the  upper  portion  into  the  brain,  then 
through  the  under  portion  to  the  end  of  the  spine. 
On  laying  open  one  side  of  the  neck,  the  carotid 
artery  was  found  beating.  On  dividing  it,  blood 
of  a much  darker  colour  than  in  the  former  expe- 
riment was  thrown  out  copiously  per  saltum. 

Exp.  6.  A rabbit  was  rendered  insensible  by 
a blow  on  the  occiput,  and  artificial  respiration 
maintained.  The  spinal  marrow  from  the  base 
of  the  skull  to  the  beginning  of  the  dorsal  verte- 
brae was  removed,  and  the  remaining  part  of  it 
destroyed  by  a hot  wire.  The  carotid  artery 
was  then  found  beating,  and,  on  dividing  it  florid 
blood  rushed  out  with  great  force  per  saltum. 

Exp.  7-  This  experiment  resembled  the  last, 
except  that  the  spinal  marrow,  instead  of  being 
partly  removed,  was  wholly  destroyed  by  a hot 


70 


wire,  and  artificial  breathing  was  not  performed 
previous  to  opening  the  carotid,  from  which  dark 
coloured  blood  flowed  per  saltum.  We  then  in- 
flated the  lungs,  and  florid  blood  soon  began  to 
flow  copiously  from  the  vessel,  and  appeared  like 
a red  stream  mixing  with  the  dark  coloured  blood 
which  had  previously  come  from  it.  This  ex- 
periment was  repeated  in  the  same  manner,  and 
with  the  same  result. 

Exp.  8.  In  this  experiment  the  rabbit  was  ren- 
dered insensible,  but  not  motionless,  by  the  blow 
on  the  occiput,  so  that  the  breathing  still  conti- 
nued. The  spine  was  opened,  and  the  spinal 
marrow  destroyed,  as  in  the  preceding  experi- 
ment. The  wire  was  used  very  hot.  On  intro- 
ducing it  through  the  spine  into  the  brain,  the 
breathing  immediately  ceased.  The  femoral 
artery  was  laid  bare  about  two  or  three  minutes 
after  respiration  had  ceased.  The  beating  of  the 
artery  was  evident.  On  opening  it,  a dark  co- 
loured blood  flowed  from  it  freely.  We  now 
had  recourse  to  artificial  respiration.  When  it 
had  been  employed  for  about  half  a minute,  the 
blood,  which  continued  to  flow  copiously  from 
the  artery,  became  of  a highly  florid  colour.  The 
other  femoral  artery  was  then  opened,  from  which 
florid  blood  also  flowed  freely.  When  about  an 
ounce  of  blood  had  flowed  from  the  two  vessels, 
the  inflation  of  the  lungs  was  discontinued,  and 
the  blood  again  flowed  of  a dark  colour.  On 


71 


renewing  the  inflation  of  the  lungs,  the  blood, 
in  less  than  half  a minute,  again  became  of  a 
florid  colour.  It  continued  to  flow  from  the  femo- 
ral arteries  altogether  for  seven  minutes.  Three 
minutes  after  the  blood  had  ceased  to  flow  from 
them,  the  artificial  respiration  being  continued, 
one  of  the  carotid  arteries  was  opened,  from 
which  a florid  blood  flowed  in  a free  stream,  to 
the  amount  of  a dram  and  a half.  The  flow  from 
the  carotid  artery  ceased  in  eleven  minutes  after 
the  femoral  artery  had  been  opened.  Most  of 
the  blood  was  now  of  course  evacuated.  A good 
deal  had  been  lost  in  opening  the  spine,  which 
always  happens.  The  left  auricle  and  ventricle 
were  found  nearly  empty.  The  blood  which 
remained  in  them  was  florid.  The  right  auricle 
and  ventricle  were  full  of  dark  blood. 

Exp.  9.  From  various  trials,  we  found  that  in 
such  experiments  the  circulation  ceases  quite  as 
soon  without,  as  with  the  destruction  of  the  spinal 
marrow.  Loss  of  blood  seems  to  be  the  chief 
cause  which  destroys  it.  If  the  animal  were 
operated  upon  without  being  rendered  insensible, 
pain  would  also  contribute  to  this  effect.  We 
frequently,  after  laying  open  the  skull  and  spine, 
found  the  circulation  lost  before  either  the  brain 
or  spinal  marrow  had  been  disturbed.  The  cir- 
culation is  particularly  apt  to  fail,  if  artificial 
respiration  is  not  carefully  performed  after  the 
animal  ceases  to  breathe.  In  making  such  ex- 


72 


periments,  after  opening  the  bone,  it  is  always 
necessary  to  ascertain  whether  the  circulation 
continues,  before  we  destroy  or  remove  the  brain 
or  spinal  marrow.  As  little  blood  is  lost  in  this 
part  of  the  operation,  when  the  carotid  arteries 
are  beating  before,  we  always  find  them  beating 
after  it.  The  result  of  this  experiment  is  still 
more  striking  in  cold  blooded  animals,  in  which 
death  takes  place  so  slowly,  that  the  circulation 
continues  long  after  the  total  destruction  of  the 
brain  and  spinal  marrow. 

Exp.  10.  The  brain  of  a frog  and  the  spinal 
marrow,  as  low  as  the  dorsal  vertebrae,  were  laid 
bare.  The  thorax  was  then  opened,  and  the 
heart  found  acting  vigorously;  and  from  the 
transparency  of  its  sides,  the  passage  of  the  blood 
through  it  distinctly  seen.  The  part  of  the  spi- 
nal marrow  which  had  been  laid  bare  w as  then 
removed,  but  without  at  all  affecting  either  the 
motion  of  the  heart,  or  the  passage  of  the  blood 
through  it.  The  brain  wTas  then  removed,  with 
the  same  result. 

Exp.  11,  The  brain  and  spinal  marrow  of  a 
frog  were  removed  at  the  same  time.  On  open- 
ing the  thorax,  the  heart  was  found  performing 
the  circulation  freely. 

It  appears  from  these  experiments  that  the  ac- 
tion of  the  heart  is  as  independent  of  every  part 
of  the  spinal  marrow  as  of  the  brain ; and,  con- 
sequently, that  the  opinion  of  M.  le  Gallois  that 


73 


it  derives  its  power  from  that  organ,  and  parti- 
cularly from  the  cervical  part  of  it,  must  be  re- 
garded as  erroneous.  I shall  soon  have  occasion 
to  consider  the  facts  which  led  M.  le  Gallois  to 
this  opinion ; we  shall  find,  I think,  that  they 
admit  of  a very  different  explanation.  We  are 
now  to  inquire  whether  the  action  of  the  vessels 
of  circulation  is  also  independent  of  the  brain 
and  spinal  marrow. 

The  following  experiments,  and  some  others 
which  I shall  have  occasion  to  relate,  were  made 
on  the  capillaries  of  the  frog,  which,  from  the  ex- 
tent and  transparency  of  the  web  of  its  hind  feet, 
and  from  its  great  tenacity  of  life,  appeared  the 
best  subject  for  such  experiments.  It  has  been 
questioned,  how  far  inferences  drawn  from  ex- 
periments made  on  cold  blooded  animals,  can  be 
supposed  to  apply  to  those  of  warm  blood.  Both 
Fontana  and  Dr.  Monro  observe,  that  in  their 
experiments  they  found  the  system  of  both  obey- 
ing the  same  laws.  The  experiments  I have  had 
occasion  to  make  on  both  sets  of  animals  tend  to 
confirm  this  observation.  There  are  certain  cir- 
cumstances in  which  they  evidently  differ,  in  all 
others  they  seem  to  agree.  As  there  is  no  part 
of  the  warm  blooded  animal  on  which  such  ex- 
periments on  the  vessels  of  circulation,  as  I shall 
have  occasion  to  relate  here  and  in  the  next 

chapter,  can  be  made  except  the  mesentery,  many 

12 


74 


of  them  would  be  attended  with  much  greater  suf- 
fering in  this,  than  in  the  cold  blooded  animal. — 
Some  of  them,  from  the  warm  blooded  animal 
being  less  tenacious  of  life,  could  not  be  so  sa- 
tisfactorily performed  on  it. 

Exp.  12.  A strong  ligature  was  thrown  round 
the  neck  of  a frog,  and  the  head  cut  off  without 
any  loss  of  blood ; much  loss  of  blood  immedi- 
ately destroys  the  circulation  in  the  extremities. 
The  spinal  marrow  was  then  destroyed  by  a 
wire.  On  bringing  the  Aveb  of  one  of  the  hind 
legs  before  the  microscope,  I found  the  circula- 
tion in  it  vigorous  for  many  minutes,  and  in  all 
respects  resembling  that  in  the  web  of  a healthy 
frog.  This  experiment  was  repeated  with  the 
same  result. 

Exp.  13.  The  spinal  marrow  of  a frog  was 
destroyed,  by  moving,  ill  various  directions,  a 
wire  introduced  into  the  spine  by  a hole  made 
in  the  lowest  part  of  it,  and  passed  up  into  the 
brain.  The  animal  was  immediately  deprived 
of  sensibility  and  voluntary  motion,  and  appear- 
ed to  be  quite  dead.  After  it  had  lain  in  this  state 
for  several  minutes,  part  of  the  web  of  one  of  the 
hind  legs  being  brought  before  the  microscope, 
the  blood  was  seen  circulating  in  it  as  rapidly  as 
in  the  web  of  a healthy  frog.  In  making  such 
experiments  it  is  necessary  to  be  aware,  that 
handling  and  stretching  the  web  tends  to  impair 
the  vigour  of  the  circulation  in  it.  If  this  expe- 


75 


riment  is  objected  to  on  account  of  its  being  made 
on  an  animal  of  cold  blood,  I may,  as  far  as  the 
larger  vessels  are  concerned,  refer  to  several  ex- 
periments just  related,  in  which  the  carotid  and 
femoral  arteries  of  rabbits  were  found  beating 
and  performing  the  circulation  after  the  sensi- 
bility had  been  destroyed  by  a blow  on  the  head, 
and  the  spinal  marrow  had  been  removed  or 
destroyed. 

It  appears  from  these  experiments  that  the 
vessels  of  circulation,  like  the  heart,  retain  their 
power  after  the  brain  and  spinal  marrow  are  de- 
stroyed or  removed,  for  it  will  hardly  be  main- 
tained, that  in  these  instances  the  power  of  the 
heart  supports  the  motion  of  the  blood  in  the 
vessels.  Should  this  opinion  be  maintained,  the 
reader  will  find  it  refuted,  respecting  animals  of 
cold  blood,  by  experiments  related  in  the  next 
chapter,  and  respecting  animals  of  warm  blood, 
by  those  related  in  chapter  tenth. 

From  the  whole  of  the  foregoing  experiments 
we  must  infer,  that  the  position  by  which  M.  le 
Grallois  explains  why  the  destruction  of  the  same 
portion  of  the  spinal  marrow  destroys  the  circu- 
lation if  suddenly  effected,  but  fails  to  do  so  if 
effected  slowly,  is  erroneous.* 

Does  it  not  seem  a necessary  inference,  from  the 
experiments  related  in  this  chapter,  that  the  action 


* See  page  54.  et  seq. 


76 

of  the  heart  and  vessels  of  circulation  depends  on 
a power  inherent  in  themselves,  and  having  no 
direct  dependence  on  the  nervous  system  ? yet 
many  facts,  laid  before  the  reader  in  the  first  part 
of  this  Inquiry,  prove  that  a certain  relation  sub- 
sists between  the  nervous  and  sanguiferous  sys- 
tems. What  this  relation  is  wre  are  now  to  in- 
quire. 


CHAP.  n. 

On  the  relation  which  subsists  between  the  heart 
and  vessels  of  circulation,  and  the  nervous  sys- 
tem. 

It  is  generally  admitted,  we  have  seen,  that  the 
action  of  the  heart  cannot  be  influenced  by  stim- 
uli applied  to  the  brain  and  spinal  marrow  : and 
it  seems  almost  a contradiction  to  suppose  that  it 
should  be  so,  when  we  see  that  it  cannot  be  in- 
fluenced by  the  total  removal  of  these  organs. 
There  were  many  reasons,  however,  which  induc- 
ed me  to  try  the  effect  on  the  heart  of  stimuli  so 
applied  to  the  brain  and  spinal  marrow,  as  not  to 
excite  any  of  the  muscles  of  voluntary  motion, 
whose  action,  both  by  throwing  more  blood  to- 
wards the  heart,  and  by  agitating  the  animal, 
prevents  our  judging  of  the  effect  of  the  stimulus. 


77 


Exp.  14.  A rabbit  was  deprived  of  sensation 
and  voluntary  motion  by  a blow  on  the  occiput, 
the  action  of  the  heart  supported  by  artificial  res- 
piration, and  the  brain  and  cervical  part  of  the 
spinal  marrow  laid  bare.  The  thorax  was  now 
opened,  and  the  action  of  the  heart,  which  beat 
with  strength  and  regularity,  observed.  Spirit 
of  wine  was  then  applied  to  the  spinal  marrow, 
and  a greatly  increased  action  of  the  heart  was 
the  consequence.  It  was  afterwards  applied  to 
the  brain  with  the  same  effect.  The  increase  of 
motion  was  immediate  and  decided  in  both  cases. 
We  could  not  perceive  that  it  was  greater  in  the 
one  case  than  the  other. 

Exp.  15.  The  foregoing  experiment  was  re- 
peated, with  the  difference,  that  the  whole  of  the 
spinal  marrow  was  laid  bare.  The  motion  of  the 
heart  was  nearly,  if  not  quite,  as  much  influenced 
by  the  application  of  the  stimulus  to  the  dorsal,  as 
to  the  cervical  portion  of  the  spinal  marrow  ; but 
it  was  very  little  influenced  by  its  application  to 
the  lumbar  portion. 

Exp.  16.  In  this  experiment,  only  that  part  of 
the  brain  which  occupies  the  anterior  part  of  the 
head  Was  laid  bare.  The  rabbit  in  other  re- 
spects was  prepared  in  the  same  way  as  in  the 
preceding  experiments.  The  spirit  of  wine  ap- 
plied to  this  part  of  the  brain,  produced  as  decid- 
ed an  effect  on  the  motion  of  the  heart  as  in  those 
experiments.  The  spirit  of  wine  was  washed  off, 


78 

and  a watery  solution,  first  of  opium,  then  of  to- 
bacco, applied,  with  the  effect  of  an  increase,  but 
a much  less  increase  of  the  heart’s  action  than 
arose  from  the  spirit  of  wine.  The  increased  ac- 
tion was  greater  from  tlie  opium  than  from  the  to- 
bacco. The  first  effect  of  both  was  soon  succeed- 
ed by  a more  languid  action  of  the  heart  than 
that  which  preceded  their  application  to  the  brain. 
This  effect  was  greatest,  and  came  on  soonest 
when  the  tobacco  was  used,  and  we  always,  for 
we  frequently  repeated  the  experiment,  saw  an 
evident  increase  in  the  action  of  the  heart  when 
we  washed  off  the  tobacco.  We  could  also  per- 
ceive this,  though  in  a less  degree,  when  the  opi- 
um was  washed  off.  Little  or  none  of  this  debili- 
tating effect  was  observed  when  the  spirit  of  wine 
was  used.  After  its  stimulating  effect  had  sub- 
sided, the  action  of  the  heart  only  returned  to 
about  the  same  degree  as  before  the  application 
of  the  stimulus. 

Eocp.  17.  The  foregoing  experiment  was  re- 
peated on  an  animal  of  cold  blood.  Mr.  Hast- 
ings had  found,  that  immersing  the  hind  legs  of  a 
frog  in  tincture  of  opium,  in  less  than  a minute 
deprives  it  of  sensibility.  This  does  not  arise 
from  any  action  of  the  opium  ; a watery  solution 
of  opium,  we  found,  however  strong,  does  not 
produce  the  effect.  It  is  immediately  produced 
by  simple  spirit  of  wine,  and  arises  from  the  ac- 
tion of  the  spirit  on  the  nerves  of  the  part  to  which 


79 


it  is  applied,  for  it  takes  plaGe  quite  as  readily  as 
in  the  healthy  frog,  after  a ligature  has  been 
thrown  round  all  the  vessels  attached  to  the  heart. 
It  is  remarkable,  that  if  simple  spirit  of  wine  is 
used,  the  animal  expresses  severe  pain ; if  tinc- 
ture of  opium,  very  little.  I have  already  men- 
tioned the  reason  why  it  is  necessary,  ill  order  to 
judge  of  the  result  of  this  experiment,  that  the 
animal  should  be  rendered  insensible.  ( Exp.  11 .) 

Having  thus  deprived  a frog  of  sensibility,  we 
laid  bare  the  brain  and  spinal  marrow,  and  open- 
ed the  chest.  The  heart  Avas  found  contracting 
Avith  vigour.  Spirit  of  Avine  was  then  applied 
to  the  spinal  marrow,  with  an  immediate  and 
evident  increase  of  the  action  of  the  heart.  It 
was  then  applied  to  the  brain  with  the  same  ef- 
fect. Watery  solutions  of  opium  and  tobacco 
Avere  also  applied  to  both,  Avith  precisely  the 
same  effect  as  in  the  rabbit.  The  increase  of 
action  from  the  opium  and  tobacco  Avas  much 
less  than  from  the  spirit  of  wine,  and  Avas  soon 
followed  by  a great  diminution  of  action.  The 
increase  of  action  Avas  least,  and  the  diminution 
greatest  from  tobacco.  On  Avashing  off  the  opium 
and  tobacco  with  a Avet  sponge,  the  heart  imme- 
diately beat  more  strongly.  The  different  parts 
of  this  experiment  were  frequently  repeated  with 
the  same  result.  It  is  remarkable  that  Ave  could 
affect  the  motion  of  the  heart  by  stimuli  applied 
to  the  brain  and  spinal  marrow,  after  they  had  all 


I 


80 


ceased  to  produce  any  effect  on  the  muscles  of 
voluntary  motion  through  the  medium  of  the  ner- 
vous system. 

Exp.  18.  This  experiment  only  differed  from 
the  last  in  the  cervical  part  of  the  spinal  marrow 
and  lower  part  of  the  brain  being  removed,  and 
the  stimuli  applied  only  to  that  part  of  the  brain 
which  lies  between  the  eyes  of  the  frog.  Spirit 
of  wine,  opium  and  tobacco,  thus  applied,  af- 
fected the  motion  of  the  heart  quite  as  much,  and 
precisely  in  the  same  way,  as  when  they  were 
applied  to  the  entire  brain  or  spinal  marrow. 
When  opium  and  tobacco  were  applied  to  the 
lower  part  of  the  spinal  marrow,  the  motion  of 
the  heart  appeared  to  be  hardly  at  all  affected  by 
them.  It  was  evidently  increased  when  spirit  of 
wine  was  applied  to  the  same  part. 

We  found  in  the  foregoing  experiments,  that 
considerable  pressure  either  of  the  brain  or  spinal 
marrow  produced  little  or  no  effect  on  the  action 
of  the  heart.  Its  action  could  be  influenced  by 
agents  applied  to  the  brain  and  spinal  marrow 
long  after  the  circulation  had  ceased. 

Thus  we  see  that  the  heart,  although  its  power 
is  independent  of  the  brain  and  spinal  marrow,  is 
capable  of  being  influenced  through  these  organs. 

All  that  has  been  said  of  the  power  of  the  heart 
is  strikingly  illustrated  by  the  following  experi- 
ments. 


81 


Exp.  19.  If  the  head  and  spinal  marrow  of  a 
frog  be  removed,  we  have  seen,  the  heart  con- 
tinues to  perform  its  function  perfectly  for  many 
hours,  nor  does  it  seem  at  all  immediately  affect- 
ed by  their  removal.  But  we  find  the  effect  very 
different  when  the  most  sudden  and  powerful 
agent  is  applied  to  them.  If  they  are  even  de- 
stroyed by  being  cut  to  pieces,  the  heart  after  their 
destruction  beats  just  as  before  it.  But  if  either 
the  brain  or  spinal  marrow  be  instantly  crush- 
ed, the  heart  immediately  feels  it.  The  thorax 
of  a large  frog  was  laid  open,  and  the  motion  of 
the  heart  observed,  which  performed  the  circula- 
tion perfectly,  and  with  great  force.  The  brain 
was  then  crushed  by  the  blow  of  a hammer.  The 
heart  immediately  performed  a few  quick  and 
weak  contractions.  It  then  lay  quite  still  for 
about  half  a minute.  After  this  its  beating  re- 
turned, but  it  supported  the  circulation  very  im- 
perfectly. In  ten  minutes  its  vigour  was  so  far 
restored  that  it  again  performed  the  circulation 
with  freedom,  but  with  less  force  than  before  the 
destruction  of  the  brain.  An  instrument  was  then 
introduced  under  the  heart,  and  after  ascertaining 
that  this  had  produced  no  change  on  its  action, 
the  spinal  marrow  was  crushed  by  one  blow,  as 
the  brain  had  been.  The  heart  again  beat  quick- 
ly and  feebly  for  a few  seconds,  and  then  seemed 
wholly  to  have  lost  its  power.  In  about  half  a 
minute  it  again  began  to  beat,  and  in  a few  mi- 

43 


82 


nutes  acquired  considerable  power,  and  again 
supported  the  circulation.  It  beat  more  feebly, 
however,  than  before  the  spinal  marrow  was  de- 
stroyed. It  ceased  to  beat  in  about  an  hour  and 
a half  after  the  brain  had  been  destroyed.  In 
another  frog,  after  the  brain  and  spinal  marrow 
had  been  wholly  removed,  the  heart  beat  nine 
hours,  gradually  becoming  more  languid. 

In  this  experiment  we  see  that  the  heart  not 
only  retains  its  power  long  after  the  brain  and 
spinal  marrow  are  removed;,  but  that  if  they  are 
destroyed  in  such  a way  as  to  impair  and  almost 
destroy  the  action  of  the  heart,  it  can  recover  the 
power  of  performing  its  function,  after  they  no 
longer  exist ; precisely  as  a muscle  of  voluntary 
motion  will  by  rest  recover  its  excitability,  al- 
though all  its  nerves  are  divided. 

Exp.  20.  The  foregoing  experiment  cannot  be 
performed  in  the  same  way  on  warm  blooded  ani- 
mals, but  it  may  be  performed  in  a way  equally 
satisfactory.  In  two  rabbits  the  brain  was  crush- 
ed by  a blow.  In  both  the  heart  immediately 
beat  with  an  extremely  feeble  and  fluttering  mo- 
tion. The  anterior  part  of  the  brain  only  was 
crushed  in  another  rabbit,  with  the  same  result. 
A strong  ligature  was  thrown  round  the  neck  of 
a fourth  rabbit,  and  at  the  moment  it  was  tighten- 
ed, the  head  was  cut  off.  The  bleeding  was  re- 
strained by  the  ligature,  except  from  the  vessels 
defended  by  the  bone.  General  spasms  made  the 


83 


body  hard  for  the  space  of  between  one  and  two 
minutes,  so  that  the  beating  of  the  heart  could  not 
be  felt.  At  the  end  of  this  time,  the  heart  was 
felt  through  the  side,  both  by  Mr.  Hastings  and 
myself,  beating  regularly,  and  not  more  quickly 
than  in  health.  All  the  rabbits  used  in  this  ex- 
periment were  of  the  same  age. 

Exp.  21.  The  following  experiment  is  still 
more  conclusive.  The  anterior  part  of  the  brain 
of  a rabbit  was  crushed  by  a blow.  The  side  was 
rendered  hard  by  a spasm  for  about  half  a minute. 
Neither  during  this,  nor  after  it,  could  I perceive 
any  motion  of  the  heart  by  applying  the  hand  to 
the  side.  The  head  was  then  cut  off,  about  three 
quarters  of  a minute  after  the  brain  had  been 
crushed.  No  blood  spouted  out,  and  very  little 
ran  from  the  vessels.  A strong  ligature  was  pass- 
ed round  the  neck  of  another  rabbit  of  the  same 
age.  It  was  suddenly  tightened,  and  the  head 
cut  off.  In  this  instance  little  spasm  took  place, 
and  the  heart  was  found  beating  regularly  under 
the  finger  for  about  three  quarters  of  a minute. 
At  the  end  of  this  time  the  ligature  was  slackened, 
and  the  blood  spouted  out  to  the  distance  of  three 
feet,  and  continued  to  spout  out  with  great  force, 
till  nearly  the  whole  blood  was  evacuated. 

Exp.  22.  From  the  strength  of  the  spine  of  a 
rabbit,  and  the  situation  of  the  neighbouring  parts, 
it  is  impossible  to  crush  it,  without  directly  influ- 
encing the  state  of  the  heart  by  the  blow.  We 


opened  it  between  the  cervical  and  dorsal  verte- 
brae, and  suddenly  forced  a steel  rod,  of  conside- 
rable thickness,  through  the  cervical  part.  As  in 
the  experiments  of  M.  le  Gallois,  the  action  of 
the  heart  was  immediately  debilitated.  In  the 
preceding  experiments,  the  reader  has  seen,  we 
repeatedly,  slowly  destroyed,  or  removed  entire- 
ly, both  the  cervical  and  other  portions  of  the  spi- 
nal marrow,  without  at  all  influencing  the  action 
of  the  heart. 

These  experiments  point  out  an  easy  solution 
of  the  difficulties  mentioned  by  M.  le  Gallois  in 
the  119th  and  following  pages  of  his  treatise. 
When  the  greater  part  of  the  spinal  marrow  was 
destroyed  by  small  portions  at  a time,  compara- 
tively little  effect  was  produced  on  the  heart ; 
but  when  a considerable  part  of  it  was  crushed 
at  once,  the  power  of  the  heart  was  so  impaired, 
that  the  circulation  ceased.  Thus  in  other  cases, 
where  the  injury  was  inflicted  slowly,  and  where 
it  was  inflicted  suddenly,  the  result  was  found  to 
be  different.  He  observes,  that  if  the  spinal  mar- 
row be  divided  near  the  occiput,  and  a certain 
part  of  it  immediately  destroyed,  the  circulation 
ceases.  If  some  time  intervene  between  the  divi- 
sion and  the  destruction  of  precisely  the  same 
part,  the  circulation  is  not  interrupted. 

In  M.  le  Gallois’  experiments,  the  spinal  mar- 
row was  always  crushed  by  a stilet,  of  precisely 
the  same  dimensions  with  the  cavity  of  the  spine. 


85 


In  the  experiments  above  related,  the  spinal  mar- 
row  was  either  removed,  or  destroyed  by  a com- 
paratively small  wire,  moved  about  in  it  till  its 
functions  ceased.  The  reader  will  easily  under- 
stand, from  what  has  been  said,  why  this  appa- 
rently slight  circumstance  occasions  so  essential 
a difference  in  the  result  of  the  experiments. 
We  have  just  seen  the  difference  of  the  result 
when  any  portion  of  the  spinal  marrow  is  suc- 
cessively destroyed  by  parts,  or  crushed  at  once, 
and  when  the  brain  is  crushed  at  once  or  wholly 
removed. 

M.  le  Gallois  maintains,  we  have  seen,  that 
affections  of  the  brain  influence  the  heart  only 
through  the  medium  of  the  spinal  marrow.  But 
in  experiment  18th,  we  have  seen,  that  after  the 
lower  part  of  the  brain  and  the  spinal  marrow  of 
a frog  had  been  removed,  agents  applied  only  to 
that  part  of  the  brain  which  lies  between  the 
eyes,  affected  the  action  of  the  heart  as  much  as 
when  applied  to  the  brain,  while  both  this  organ 
and  the  spinal  marrow  were  entire.  To  remove 
any  objection  which  may  arise  from  the  subject  of 
this  experiment  having  been  an  animal  of  cold 
blood,  the  following  was  made. 

Exp.  23.  I divided  the  spine  of  a rabbit  near 
the  head,  (which  by  stopping  the  respiration  de- 
prived the  animal  of  sensibility  and  voluntary 
power,)  and  then  at  the  lower  end,  and  by  means 
of  a wire,  introduced  at  these  parts,  destroyed 


8(5 


the  spinal  marrow.  Spirit  of  wine  was  then  ap 
plied  to  the  brain,  which  influenced  the  action  of 
the  heart  as  readily,  and  to  as  great  a degree,  as 
it  does  when  the  spinal  marrow  is  entire. 

We  are  now  to  inquire  how  far  the  vessels 
of  circulation  are  capable  of  being  influenced 
through  the  brain  and  spinal  marrow. 

In  order  to  ascertain  whether  the  vessels  can 
be  stimulated  through  these  organs  independently 
of  their  action  on  the  heart,  it  is  necessary  in  the 
first  place  to  determine  how  far  the  vessels  can 
support  the  motion  of  the  blood  independently  of 
the  heart. 

M.  Bichat  ( Recherches  Phys.  sur  la  vie  et  la 
mort.J  has  shewn  that  in  a frog  the  motion  of 
the  blood  continues  in  the  capillaries  after  the 
heart  no  longer  propels  it.  This  observation, 
indeed,  we  shall  afterwards  find  applies  to  the 
warm,  as  well  as  the  cold  blooded  animal. 

Exp.  S4.  A ligature  was  thrown  round  all  the 
vessels  attached  to  the  heart  of  a frog,  and  the 
heart  was  then  cut  out.  On  bringing  the  web  of 
one  of  the  hind  legs  before  the  microscope,  the 
circulation  in  it  was  found  to  be  vigorous,  and 
continued  so  for  many  minutes ; at  length  gradu- 
ally becoming  more  languid. 

In  endeavouring  to  proceed  further,  I found 
much  difficulty.  It  was  not  only  necessary,  in 
order  to  ascertain  the  effect  of  stimuli  applied  to 


87 


the  brain  or  spinal  marrow  on  the  vessels  of  the 
web,  to  remove  the  heart,  and  to  lay  open  the  cra- 
nium, but  also  to  prevent  the  voluntary  motions  of 
the  animal,  which  continually  occur,  and  never 
fail  to  accelerate  the  motion  of  the  blood  in  the 
web. 

Exp . 25.  A frog  was  deprived  of  sensibility 
and  voluntary  motion,  by  the  upper  parts  of  the 
body  being  immersed  in  laudanum ; part  of  the 
cranium  was  then  removed,  after  a ligature  had 
been  thrown  round  the  neck  to  prevent  loss  of 
blood.  The  thorax  was  now  opened,  and  all  the 
vessels  attached  to  the  heart  included  in  a liga- 
ture. But,  notwithstanding  this  experiment  was 
repeatedly  performed  with  the  greatest  care,  the 
circulation  by  all  these  preparatory  means  was  so 
enfeebled,  that  although  the  blood  still  moved  in 
the  web,  it  was  in  so  irregular  and  uncertain  a 
way,  that  I never  could  arrive  at  any  positive 
conclusion  respecting  the  effect  of  the  stimulus 
applied  to  the  brain.  After  many  fruitless  at- 
tempts, therefore,  I abandoned  this  mode  of  mak- 
ing the  experiment. 

Although  the  action  both  of  the  heart  and  the 
muscles  of  voluntary  motion  so  influence  the  ef- 
fect of  stimuli  applied  to  the  brain,  on  the  circu 
lation  in  the  foot,  that,  without  wholly  preventing 
the  effect  of  both,  no  conclusion  can  be  drawn,  it 
is  evident  that  the  action  of  the  latter  cannot  in- 


88 


crease  the  effect  of  sedatives ; and  the  sedative 
lessening  the  power  of  the  heart  will  not  affect 
the  result  of  the  experiment,  if  it  be  made  on  the 
web  of  the  frog.  We  have  just  seen,  that  the 
total  ceasing  of  the  action  of  the  heart  does  not, 
for  a considerable  time,  affect  the  circulation  in  it. 
The  following  experiments  appear  to  be  decisive 
of  the  effect  of  the  sedative,  and  of  the  stimulus, 
as  far  as  this  can  be  decisive,  the  action  of  the 
heart  remaining.  It  is  evident  that  the  action  of 
either  stimulus  or  sedative  is  equally  conclusive 
respecting  the  direct  influence  of  the  nervous  sys- 
tem on  the  blood  vessels. 

j Exp.  26.  Part  of  the  cranium  of  a frog  was 
removed,  the  web  of  one  of  the  hind  legs  brought 
before  the  microscope,  and  the  circulation  in  it 
observed.  The  animal  was  now  rendered  insen- 
sible by  the  immersion  of  the  other  hind  leg  in 
laudanum.  The  insensibility  did  not  in  the  least 
affect  the  circulation  in  the  web  before  the  micro- 
scope. Spirit  of  wine  was  then  applied  to  the 
brain  with  an  evident  increase  of  the  velocity  of 
the  blood  in  the  web.  The  same  effect  was  pro- 
duced in  a less  degree  by  watery  solutions  of 
opium  and  tobacco.  After  the  tobacco  had  been 
applied  for  about  half  a minute,  the  motion  of  the 
blood  was  much  less  rapid  than  before  its  appli- 
cation. On  washing  off  the  tobacco  the  velocity 
of  the  blood  increased,  and  was  again  lessened 


89 


on  applying  it.  This  was  repeated  several  times 
with  the  same  effects.  The  following  way  of 
performing  the  experiment  is  equally  conclusive. 

Exp.  27.  A frog  was  rendered  nearly  insen- 
sible by  having  its  back  immersed  in  laudanum. 
A ligature  was  then  thrown  round  the  neck  to 
prevent  loss  of  blood,  part  of  the  cranium  remov- 
ed, the  web  of  one  of  the  hind  legs  brought  be- 
fore the  microscope,  and  the  circulation  in  it 
which  was  rapid,  observed.  A strong  infusion 
of  tobacco  was  then  applied  to  the  brain,  with 
the  effect  of  at  first  rendering  the  circulation  more 
rapid.  In  about  half  a minute  it  became  more 
languid,  and  soon  stopped  altogether.  On  the 
infusion  of  tobacco  being  washed  off,  the  cir- 
culation returned  nnd  regained  considerable  vi- 
gour. The  tobacco  was  several  times  applied  to 
the  brain  and  washed  off,  with  the  same  effects. 
I may  observe,  that  when  the  circulation  in  the 
web  had  almost  ceased  after  the  tobacco  had  been 
washed  off,  its  velocity  was  immediately  increas- 
ed on  applying  spirit  of  wine  to  the  brain. 

Exp.  28.  Analogous  to  what  I had  occasion 
to  observe  respecting  the  heart,  I could  never, 
either  by  chemical  or  mechanical  agents,  excite 
any  irregular  action  in  the  blood  vessels.  Their 
action  was  only  rendered  more  or  less  powerful. 

The  irregular  appearances  in  the  circulation 
in  the  web  of  a frog’s  foot,  mentioned  by  Dr. 

Thompson,  Professor  of  Military  Surgery  in  the 

14 


90 


University  of  Edinburgh,  in  his  Lectures  on  In- 
flammation lately  published,  and  which  he  as- 
cribes to  inflammation,  may  be  observed  in  any 
case,  if  the  vessels  be  at  all  compressed  in  apply- 
ing the  foot  to  the  microscope ; and  although  they 
are  not  compressed,  these  appearances  very  gene- 
rally occur  when  the  circulation  begins  to  fail. 
The  blood  will  then  stop  and  go  on  at  intervals, 
and  move  backwards  and  forwards  in  the  same 
vessel.  I have  often  watched  the  capillaries  from 
the  commencement  of  inflammation  to  its  greatest 
height,  when  the  part  is  about  wholly  to  lose  its 
vital  power,  in  the  mesentery  of  a rabbit,  the 
Web  of  a frog’s  foot,  and  the  fins  of  fishes,  with- 
out perceiving  the  least  tendency  to  this  irregular 
motion  when  the  part  viewed  was  so  applied  to 
the  microscope  as  not  to  compress  any  of  its  ves- 
sels.* When  the  circulation  fails  without  any 
morbid  distension  of  the  vessels,  the  motion  of  the 
blood  in  the  small  vessels  is  irregular  before  it 
stops  altogether ; when  it  fails  from  morbid  dis- 
tension of  the  vessels,  which  gives  rise  to  the 
phenomena  of  inflammation,  this  irregularity  is 
not  perceived,  the  motion  of  the  blood  gradually 
becomes  slower  till  it  ceases  altogether. 

The  power  of  the  blood  vessels,  like  that  of 

* An  account  of  these  experiments  is  published  in  the  in- 
troduction to  the  second  part  of  my  Treatise  on  Febrile  Dis- 
eases, and  a plate  given  representing  the  state  of  the  vessels 
in  the  different  stages  of  inflammation. 


& 


01 


the  heart,  is  capable  of  being  directly  destroyed 
through  the  medium  of  the  nervous  system. 

Exp.  29.  The  web  of  one  of  the  hind  legs  of 
a frog  was  brought  before  the  microscope,  and 
while  Mr.  Hastings  observed  the  circulation, 
which  was  vigorous,  I crushed  the  brain  by  the 
blow  of  a hammer.  The  vessels  of  the  web  in- 
stantly lost  their  power,  the  circulation  ceasing. 
In  a short  time  the  blood  again  began  to  move, 
but  with  less  force.  This  experiment  was  re- 
peated with  the  same  result.  If  the  brain  is  not 
completely  crushed,  the  blow  increases  the  ra- 
pidity of  the  circulation  in  the  web.  ^ 

Exp.  30.  The  spine  of  a frog  was  laid  open 
at  the  lower  end,  and  a wire  of  nearly  the  same 
dimensions  with  its  cavity,  forced  through  it,  as 
in  M.  le  Grallois’  experiments.  The  web  of  one 
of  the  hind  legs  was  then  brought  before  the  mi- 
croscope, and  the  circulation  in  it  was  found  to 
have  wholly  ceased.  In  another  frog,  as  we 
have  seen,*  the  spinal  marrow  was  destroyed 
by  introducing  in  the  same  way,  and  moving  in 
various  directions,  a wire  much  smaller  than  the 
cavity  of  the  spine.  The  frog  soon  appeared  to 
be  quite  dead,  but  the  circulation  in  the  web  was 
found  to  be  vigorous. 

What  are  the  simple  results  of  the  experi- 


* See  Experiment  13. 


ments  related  iu  this  and  the  preceding  chapter? 
The  first  set  prove,  that  the  power  of  the  heart 
and  vessels  of  circulation  is  independent  of  the 
brain  and  spinal  marrow,  for  we  find  that  the 
functions  of  the  former  organs  continue  after  the 
latter  are  destroyed  or  removed,  and  that  their 
removal  is  not  attended  with  any  immediate  effect 
on  the  motions  of  the  heart  and  vessels.  The 
second  set  prove,  that  the  action  of  the  heart  and 
vessels  of  circulation  may  be  influenced  by  agents 
applied  either  to  the  brain  or  spinal  marrow.  It 
is  as  readily  influenced  by  agents  applied  to  the 
anterior  part  of  the  brain,  as  by  those  applied  to 
the  cervical  part  of  the  spinal  marrow.  This  is 
what  we  should  expect  when  we  trace  the  origins 
of  their  nerves. 

If  it  be  said  that  the  results  of  these  experi- 
ments imply  a contradiction,  that  we  cannot  sup- 
pose the  power  of  the  heart  aud  vessels  to  be 
wholly  independent  of  the  brain  and  spinal  mar- 
row, and  yet  influenced  by  stimuli  applied  to 
them,  the  reply  is,  that  such  are  the  facts,  of  the 
truth  of  which  any  one  may  easily  satisfy  him- 
self. 

On  a closer  examination  of  the  phenomena  of 
the  nervous  system,  we  shall  find  other  similar 
difficulties.  The  experiments  of  M.  le  Gallois 
prove,  in  the  most  satisfactory  manner,  that  a 
principal  function  of  the  spinal  marrow7  is  to  ex- 
cite the  muscles  of  voluntary  motion,  and  that  it 


93 


can  perform  this  office  independently  of  the  brain. 
It  performs  it  after  the  brain  is  wholly  removed, 
and  its  powers  seem  not  at  all  immediately  im- 
paired by  the  removal  of  the  brain ; yet  we  con- 
stantly see  injuries  of  the  brain  impairing  the 
functions  of  the  spinal  marrow.  We  may  re- 
move the  brain,  and  the  animal  performs  the  va- 
rious motions  of  its  limbs  as  well  as  before  its  re- 
moval. Yet  an  injury  of  the  brain  often  deranges 
the  function  of  the  spinal  marrow.  Of  this  ap- 
parent inconsistency,  M.  le  Gallois  justly  re- 
marks, that  two  facts  well  ascertained,  however 
inconsistent  they  may  seem,  do  not  overturn  each 
other,  but  only  prove  the  imperfection  of  our 
knowledge. 

Whichever  of  the  disputed  opinions  respecting 
the  functions  of  the  nervous  system  we  adopt,  the 
foregoing  phenomena  seem  to  imply  a contradic- 
tion. The  experiments  related  in  the  following 
chapter  point  out  still  another  instance  of  this  ap- 
parent contradiction,  and  seem  to  suggest  the 
principle  on  which  it  as  well  as  the  others  depend. 


94 


CHAP.  III. 

On  the  principle  on  which  the  action  of  the  mus- 
cles of  voluntary  motion  depends , and  the  re- 
lation which  they  bear  to  the  nervous  system. 

We  are  now  to  consider  how  far  the  principle 
on  which  the  action  of  the  muscles  of  voluntary 
motion  depends,  and  the  relation  which  they  bear 
to  the  nervous  system,  resemble  those  of  the  heart 
and  vessels  of  circulation. 

Exp.  31.  By  applying  strong  stimuli  to  the 
spinal  marrow  of  a frog,  strong  and  repeated  con- 
tractions were  excited  in  the  muscles  of  the  hind 
limbs,  as  long  as  the  stimuli  would  produce  the 
effect.  On  examining  the  state  of  the  muscles  of 
these  limbs,  I found  them  wholly  deprived  of 
their  excitability.  Now  it  is  well  known,  that 
although  all  the  nerves  supplying  the  limbs  of  a 
frog  be  divided,  and  cut  out  close  to  the  place 
where  they  enter  the  muscles,  the  latter  still  re- 
tain their  excitability,  which  appears  to  be  not  at 
all  less  than  when  the  nerves  are  entire.  Lest  it 
may  be  supposed  that  the  nervous  influence, 
which  was  exhausted  in  this  experiment  by  stimu- 
lating the  spinal  marrow,  still  remains  in  the  mus- 
cles after  the  nerves  are  divided,  and  thus  pre- 
serves their  excitability,  the  following  experiment 
was  made. 


95 


Exp.  33.  All  the  nerves  supplying  one  of  the 
hind  limbs  of  a frog  were  divided,  so  that  it  be- 
came completely  paralytic.  The  skin  was  re- 
moved from  the  muscles  of  the  leg,  and  salt 
sprinkled  upon  them,  w hich,  being  renewed  from 
time  to  time,  excited  contractions  in  them  for 
twelve  minutes  ; at  the  end  of  this  time  they  were 
found  no  further  capable  of  being  excited.  The 
corresponding  muscles  of  the  other  limb,  in  which 
the  nerves  w ere  entire,  and  of  which  consequently 
the  animal  had  a perfect  command,  were  then 
laid  bare,  and  the  salt  applied  to  them  in  the 
same  way.  In  ten  minutes  they  ceased  to  con- 
tract, and  the  animal  had  lost  the  command  of 
them.  The  nerves  of  this  limb  were  now  divid- 
ed, as  those  of  the  other  had  been,  but  the  excita- 
bility of  the  muscles  to  w hich  the  salt  had  been 
applied  was  gone.  Its  application  excited  no  con- 
traction in  them.  It  sometimes  happens,  while 
the  nerves  of  the  limb  are  entire,  that  the  volun- 
tary efforts  of  the  animal  prevent  the  contractions 
usually  excited  by  the  application  of  salt.  This 
experiment  was  repeated  in  the  same  manner, 
and  with  a similar  result.  After  the  experiment, 
the  muscles  of  the  thighs  in  both  limbs  were 
found  to  contract  forcibly  on  the  application  of 
salt.  It  excited  equally  strong  contractions  on 
both  sides. 

It  is  remarkable,  that  in  this  experiment,  the 
excitability  of  the  muscles  whose  nerves  were  en- 


96 


tire,  was  soonest  exhaused.  In  the  repetition  of 
the  experiment,  this  was  the  case  to  a still  greater 
degree' ; the  muscles,  whose  nerves  were  entire, 
losing  their  excitability  in  about  one  half  of  the 
time  required  for  exhausting  the  other. 

From  this  experiment  it  is  evident,  that  the 
nervous  influence,  so  far  from  bestowing  excit- 
ability on  the  muscles,  exhausts  it,  like  other 
stimuli.  The  excitability,  therefore,  is  a property 
of  the  muscle  itself.  Yet  we  have  just  seen,  that 
it  may  be  wholly  destroyed  by  changes  induced 
on  the  nervous  system.  On  the  same  principle 
we  explain  the  seeming  contradiction  respecting 
the  action  of  the  heart  and  vessels.  We  have 
seen  that  their  power  exists  as  independently  of 
the  brain  and  spinal  marrow,  as  the  action  of  the 
first  muscles  to  which  the  salt  was  applied,  whose 
nerves  had  been  divided ; but,  while  the  brain 
and  spinal  marrow  retain  their  functions,  and 
the  connection  of  nerves  is  entire,  the  heart  and 
vessels,  as  well  as  the  muscles  of  voluntary  mo- 
tion, may  be  influenced  by  agents  acting  through 
the  nervous  system.  It  is  not  difficult  to  account 
for  the  latter  muscles  being  more  copiously  sup- 
plied with  nerves  than  the  heart,  because  all 
the  stimuli  which  affect  them,  act  through  their 
nerves,  while  the  heart  is  only  now  and  then  in- 
fluenced through  its  nerves,  its  usual  stimulus 
being  as  immediately  applied  to  it,  as  the  salt 
was  to  the  muscles  of  the  limb  in  the  above  ex- 


97 


periment,  and  acting  as  independently  of  the 
nervous  system.  We  do  not  surely,  in  the  ex- 
periments which  have  been  laid  before  the  reader, 
see  any  difference  in  the  nature  of  the  muscular 
power  of  the  heart,  and  that  of  the  muscles  of 
voluntary  motion,  except  their  being  fitted  to 
obey  different  stimuli,  a difference  which  we 
find  in  the  two  sides  of  the  heart  itself. 

It  may  here  be  objected,  that  in  apoplexy  the 
poAver  of  the  muscles  of  voluntary  motion  is  lost, 
while  that  of  the  heart  is  little,  or  not  at  all,  im- 
paired. Were  such  the  fact,  this  objection  would 
be  unanswerable;  but  I have  repeatedly  examin- 
ed the  state  of  the  muscles  of  voluntary  motion 
in  apoplexy,  both  in  warm  and  cold  blooded  ani- 
mals, and  found  their  excitability  unimpaired. 
It  is  not  their  power,  but  the  stimulus  which 
excites  them,  that  is  lost  in  apoplexy.  In  this 
disease  the  heart  continues  to  contract,  because 
its  stimulus  is  still  supplied;  the  muscles  of  vo- 
luntary motion  cease  to  contract,  because  their 
stimulus  is  withdrawn.* 

The  conclusions  afforded  by  the  foregoing  ex- 
periments so  far  agree  with  those  of  Haller,  that 
they  prove  the  heart  and  other  muscles  to  pos- 
sess an  excitability  independent  of  the  nervous 
system ; but  they  prove,  contrary  to  the  opinion 


* See  Chap.  10. 
15 


98 


of  that  great  Physiologist,  that  the  heart  is, 
equally  with  the  muscles  of  voluntary  motion, 
capable  of  being  stimulated  through  this  system. 

In  the  report  of  the  National  Institute  of 
France,  which  has  been  laid  before  the  reader,  it 
is  observed,  <(  the  adversaries  of  irritability  have 
asked,  why,  if  the  nervous  power  has  no  action 
on  the  heart,  is  this  organ  supplied  with  nerves, 
and  why  it  is  so  powerfully  subjected  to  the  in- 
fluence of  the  passions  ? Haller  never  gave  any 
satisfactory  explanation  of  these  objections,  but 
every  thing  proves  that  he  felt  all  their  force.” 
These  objections,  we  have  seen,  prevented  Hal- 
ler’s doctrine  of  irritability  from  being  generally 
admitted  by  Physiologists,  and  at  length  led  M. 
le  Gallois  to  suppose  that  he  had  wholly  refut- 
ed it. 

We  may,  I think,  trace  the  subject  further.  It 
has  been  shewn  by  direct  experiment,  by  M.  le 
Gallois,  that  the  spinal  marrow  is  capable  of  per- 
forming its  functions  independently  of  the  brain, 
yet,  as  has  been  observed,  the  spinal  marrow 
may  be  influenced  through  the  brain.  Thus  the 
excitability  of  the  spinal  marrow  bears  the-  same 
relation  to  the  brain,  which  that  of  the  muscles 
bears  to  the  spinal  marrow  and  its  nerves,  and  I 
would  add  all  nerves  distributed  to  muscles, 
some  of  which  arise  from  the  brain,  but  seem  to 
bear  precisely  the  same  relation  to  the  sensorium 
and  to  the  muscles,  with  those  which  arise  from 


99 


the  spinal  marrow.  Even  M.  le  Gallois,  although 
his  experiments  lead  to  an  opposite  conclusion,* 
observes,  that  the  brain  seems  to  act  on  the  spinal 
marrow  as  the  latter  does  on  the  parts  it  ani- 
mates. We  know  the  peculiar  office  of  the  brain, 
by  observing  what  functions  are  lost  by  its  re- 
moval, the  sensorial  functions.  The  nervous, 
then,  obeys  the  sensorial  system,  in  the  same  way 
in  which  the  muscular  obeys  the  nervous  system  ; 
but  as  the  muscular  power  has  an  existence  inde- 
pendent of  the  nervous,  so  has  the  nervous  an  ex- 
istence independent  of  the  sensorial  power. 

I shall,  towards  the  latter  part  of  this  inquiry, 
endeavour  to  point  out  with  more  precision  than 
has  been  done,  the  line  of  distinction  between  the 
sensorial  and  nervous  functions,  which  appears 
to  me  from  direct  experiments,  to  be  very  dif- 
ferent from  that  assumed  by  M.  le  Gallois. f 

* He  infers  from  his  experiments  that  the  power  of  the 
heart  ceases  on  the  destruction  of  the  spinal  marrow,  but 
that  that  of  the  spinal  marrow  remains  after  the  destruction 
of  the  brain. 

t See  Chap.  10. 


100 


CHAP.  IV. 

On  the  comparative  effects  of  stimuli  applied  to 
the  brain  and  spinal  marrow  on  the  heart  and 
muscles  of  voluntary  motion. 

In  making  the  experiments  related  in  the  pre- 
ceding chapters  it  was  evident,  that  although  the 
muscles  of  involuntary  are  equally  w ith  those  of 
voluntary  motion  subject  to  the  effects  of  stimuli 
applied  to  the  brain  aud  spinal  marrow,  the  laws 
which  regulate  these  effects  on  the  two  sets  of 
muscles  are  very  different.  The  following  ex- 
periments point  out  more  precisely  in  what  this 
difference  consists. 

Exp.  33.  Part  of  the  cranium  of  a rabbit  was 
removed,  and  a w ire  passed  in  various  directions 
through  the  brain.  I could  not  in  this  way  in 
the  least  affect  the  muscles  of  voluntary  motion, 
except  when  I made  the  wire  approach  those 
parts  of  the  brain  from  which  tlie  spinal  marrow 
and  nerves  originate.  The  muscles  of  voluntary 
motion  were  then  tin-own  into  violent  spasms. — 
I sliced  off  the  w hole  of  the  upper  and  anterior 
part  of  the  brain  without  affecting  the  muscles  of 
voluntary  motion.  The  knife  only  excited  their 
action  when  it  approached  the  source  of  the 
nerves  and  spinal  marrow-. 

Exp.  34.  Having  deprived  another  rabbit  of 


101 


sensibility  and  voluntary  motion  by  a blow  on 
the  occiput,  that  I might  be  enabled  to  judge  of 
the  effects  which  a stimulus  applied  to  the  brain 
would  produce  on  the  heart,  I removed  part  of 
the  cranium  and  laid  open  the  thorax.  The  heart 
was  found  beating  regularly.  By  passing  a wire 
through  the  brain  in  any  direction,  the  beats  of 
the  heart  were  accelerated  and  rendered  stronger. 
I could  not  perceive  that  this  effect  was  produced 
more  powerfully  when  the  wire  was  directed  to- 
wards the  source  of  the  nerves,  than  when  any 
other  direction  was  given  to  it,  provided  it  passed 
through  an  equal  portion  of  the  brain.  When 
an  instrument  was  merely  pressed  on  the  surface 
of  the  brain,  the  effect  was  similar.  When  a 
pair  of  scissars,  or  any  other  thing  of  larger  bulk 
than  the  wire  was  passed  into  the  brain,  the  effect 
on  the  heart  was  greater  than  from  the  wire.  It 
was  still  greater  when  the  brain  was  wounded 
rapidly  in  many  directions. 

Exp.  35.  Part  of  the  cranium  of  a rabbit  was 
removed,  and  after  passing  a knife  through  the 
brain  in  various  directions  towards  the  origin  of 
the  nerves,  which  excited  the  strongest  spasms 
in  the  muscles  of  voluntary  motion,  the  blood 
being  absorbed  by  a sponge,  I applied  strong 
spirit  of  wine  to  the  surface  of  the  brain,  and 
dropt  it  into  the  cuts,  without  at  all  affecting  the 
muscles  of  voluntary  motion.  The  upper  part  of 
the  brain  was  then  wholly  removed,  and  the 


102 


space  filled  with  strong  spirit  of  wine,  hut  no 
spasms  were  excited  in  the  muscles  of  voluntary 
motion. 

Exp.  36.  Another  rabbit  was  deprived  of  sen- 
sibility and  voluntary  motion  by  a blow  on  the 
occiput.  Part  of  the  cranium  was  then  removed, 
the  thorax  laid  open,  and  the  heart  found  beating 
regularly.  Spirit  of  wine  was  uow  applied  to 
the  surface  of  the  brain,  by  which  the  frequency 
and  force  of  the  heart’s  beats  were  immediately 
increased.  Several  cuts  were  then  made  in  the 
brain,  and  the  spirit  of  wine  dropt  into  them,  by 
which  the  action  of  the  heart  was  increased  in  a 
much  greater  degree.  Spirit  of  wine  increased 
the  action  of  the  heart  more  than  any  mechanical 
injury,  which  never  produced  the  strong  action  in 
this  organ,  that  it  does  in  the  muscles  of  volun- 
tary motion. 

This  experiment  was  repeated  with  a watery 
infusion  of  opium  instead  of  spirit  of  wine ; the 
result  was  in  all  respects  the  same,  except  that 
the  action  of  the  heart  was  less  increased  than  by 
the  spirit  of  wine. 

Under  the  term  brain,  I mean  to  include  the 
cerebellum  as  well  as  cerebrum.  From  many 
trials  on  rabbits  made  to  ascertain  the  point,  I 
could  not  perceive  that  the  heart  is  more  or  less 
affected  either  by  chemical  or  mechanical  stimuli 
applied  to  the  cerebellum  than  to  the  cerebrum ; 
nor  are  the  muscles  of  voluntary  motion  affected 


103 


by  wounding  the  cerebellum,  except  we  approach 
the  source  of  the  spinal  marrow  and  nerves.  In 
some  of  my  experiments,  I thought  that  stimuli 
applied  to  the  cerebellum  affected  the  action  of 
the  heart  rather  more  powerfully  than  when  ap- 
plied to  the  cerebrum  ; but  this  was  contradicted 
by  other  experiments. 

Exp.  37-  I repeatedly  cut  off  the  head  of  a 
rabbit  close  to  the  occiput.  For  some  time  the 
trunk  and  limbs  were  affected  with  violent 
spasms.  The  cut  end  of  the  spinal  marrow  was 
so  sensible  that  the  slightest  touch  of  a wire,  af- 
ter the  spasms  had  subsided,  immediately  excited 
the  action  of  the  muscles  of  voluntary  motion. 
The  strongest  spirit  of  wine  and  watery  infusion 
of  opium  were  applied  to  it,  without  producing 
the  least  effect  on  those  muscles.  The  applica- 
tion, however,  of  stronger  chemical  stimuli,  the 
nitric  and  muriatic  acids,  threw  the  muscles  of 
the  fore-legs  into  powerful  contractions. 

Having  deprived  a rabbit  of  sensation  and  vo- 
luntary motion,  in  an  experiment  already  related, 
I found  that  both  spirit  of  wine  and  a watery  in- 
fusion of  opium  applied  to  the  spinal  marrow,  in- 
crease the  action  of  the  heart. 

Exp.  38.  I found  both  in  rabbits  and  frogs 
that,  after  all  stimuli  applied  either  to  the  brain 
or  spinal  marrow  had  ceased  to  produce  any  ex- 
citement in  the  muscles  of  voluntary  motion,  both 
chemical  and  mechanical  stimuli  so  applied  still 


104 

increased  the  action  of  the  heart : the  former- 
more  than  the  latter. 

Exp.  39.  I tried,  in  every  possible  way,  both 
by  mechanical  and  chemical  stimuli,  and  both 
before  and  after  the  sensibility  was  destroyed, 
to  excite,  through  the  brain  or  spinal  marrow  of 
rabbits  and  frogs,  any  irregular  action  in  the 
heart  which  is  so  readily  excited  in  the  muscles 
of  voluntary  motion,  but  could  not.  Nor  could 
I by  sedatives,  applied  to  the  nervous  system, 
occasion  any  irregular  action  in  the  heart.  Its 
action  was  rendered  quicker  or  slower,  more  or 
less  frequent,  stronger  or  weaker,  but  never  ir- 
regular. The  only  instance  in  which  irregular 
action  was  excited  in  the  heart,  was  when  its 
power  was  nearly  destroyed  by  crushing  the 
brain  or  spinal  marrow. 

Exp.  40.  I found  from  many  trials  both  on 
rabbits  and  frogs,  that  the  excitement  of  the  mus- 
cles of  voluntary  motion  took  place  chiefly  at  the 
time  the  stimulus  was  applied  to  the  brain  or 
spinal  marrow.  It  was  generally  necessary  to 
move  the  instrument;  thus  applying  it  to  a uew 
surface  in  order  to  support  the  effect.  Repeated 
contractions  of  the  muscles  of  voluntary  motion 
will  sometimes  continue,  assuming  the  form  of  a 
fit,  as  long  as  the  instrument  remains  in  the  brain, 
although  it  be  kept  as  still  as  the  motions  of  the 
animal  will  admit  of.  The  increased  action  of 
the  heart  on  the  contrary,  could  generally  be  ob- 


105 


served  as  long  as  the  stimulus,  whether  chemical 
or  mechanical,  was  applied,  unless  it  was  of  a 
nature  to  produce  the  sedative,  after  the  stimu- 
lant effect.  The  sedative  effect  is  so  far  from 
being  the  consequence  of  the  previous  excite- 
ment, as  many  physiologists  have  supposed,  that 
spirit  of  wine  and  mechanical  stimuli,  which 
produced  no  sedative  effect,  but  continued  to 
stimulate  the  heart  as  long  as  they  were  applied, 
produced  a much  greater  degree  of  excitement 
than  tobacco,  whose  slight  stimulant  effect  was 
quickly  succeeded  by  a powerful  sedative  one. 

It  appears  from  these  experiments,  that  che- 
mical stimuli,  applied  to  the  brain  and  spinal 
marrow,  exert  a greater  power  over  the  heart 
than  mechanical  stimuli,  while  the  latter  exert 
a greater  power  over  the  muscles  of  voluntary 
motion  than  chemical  stimuli;  that  both  chemi- 
cal and  mechanical  stimuli,  applied  to  the  brain 
and  spinal  marrow,  excite  the  heart,  after  they 
cease  to  produce  any  effect  on  the  muscles  of 
voluntary  motion  ; that  stimulating  every  part  of 
the  brain  and  spinal  marrow  equally  affects  the 
action  of  the  heart,  while  the  muscles  of  volun- 
tary motion  are  only  excited  by  stimuli  applied 
to  the  parts  of  those  organs  from  which  their 
nerves  originate;  that  stimuli  applied  to  the 
brain  and  spinal  marrow  never  excite  irregular 
action  of  the  heart,  while  nothing  can  be  more 

than  the  action  they  excite  in  the  mus- 
16 


106 


cles  of  voluntary  motion ; that  their  effect  on  these 
muscles  is  felt  chiefly  on  their  first  application, 
but  continues  on  the  heart  as  long  as  the  stimu- 
lus is  applied.  These  differences  in  the  effects 
of  stimuli  applied  to  the  brain  and  spinal  mar- 
row on  the  muscles  of  voluntary,  and  those  of 
involuntary  motion,  must  be  explained  before 
we  can  be  said  to  understand  the  relation  which 
subsists  between  the  nervous  system  and  the 
heart. 

It  appeared  to  me  probable,  from  many  expe- 
riments, that  the  cause  of  chemical  stimuli,  ap- 
plied to  the  nervous  system,  producing  a greater 
effect  on  the  heart  than  mechanical  stimuli  do,  is, 
that  the  former,  from  their  nature,  act  on  a larger 
portion  of  the  brain  and  spinal  marrow.  If  this 
opinion  be  correct,  the  mechanical  stimulus  will 
be  rendered  the  most  powerful  by  confining  the 
chemical  to  a smaller  space  than  the  mechanical 
stimulus  occupies. 

Exp.  41.  Both  in  frogs  and  rabbits  I applied 
to  various  parts  of  the  brain  and  spinal  marrow, 
and  particularly  to  those  parts  from  which  the 
nerves  originate,  minute  portions  of  strong  spirit 
of  wine,  without  at  all  influencing  the  action  of 
the  heart.  When  these  small  portions  were  ap- 
plied to  a great  many  parts,  the  heart  began  to 
beat  more  frequently.  This  of  course  was  much 
the  same  thing  as  at  once  applying  the  spirit  of 
wine  to  a larger  part.  We  have  seen  in  the  fore- 


107 


going  experiments,  that  mechanical  stimuli  ap- 
plied to  any  considerable  portion  of  the  nervous 
system,  increase  the  action  of  the  heart.  It  ap- 
pears from  the  following  experiments  that  we 
cannot  affect  the  heart  by  mechanical  stimuli  con- 
fined to  any  small  part  either  of  the  brain  or 
spinal  marrow. 

Exp.  42.  In  a rabbit  deprived  of  sensibility  by 
a blow  on  the  occiput,  I wounded  different  small 
parts  of  the  brain  with  a wire,  particularly  all 
those  parts  near  which  the  nerves  of  the  heart 
appear  chiefly  to  originate ; but  could  not  affect 
the  motion  of  this  organ,  while  at  the  same  time 
passing  the  wire  through  any  considerable  por- 
tion of  the  brain  immediately  accelerated  it. 

Exp.  43.  I laid  open  the  cervical  part  of  the 
spine  of  a rabbit,  rendered  insensible  by  a blow 
on  the  occiput,  and  repeatedly  passed  the  wire 
transversely  through  the  spinal  marrow,  without 
being  able  at  all  to  affect  the  motion  of  the  heart ; 
but  on  a wire  being  passed  longitudinally,  so  as 
to  bring  it  into  contact  with  a larger  portion  of  the 
spinal  marrow,  the  motion  of  the  heart  was  im- 
mediately accelerated.  On  the  same  principle, 
when  the  wire  was  made  to  wound  many  minute 
portions  of  the  brain  and  spinal  marrow  in  quick 
succession,  the  action  of  the  heart  was  increased. 
In  another  rabbit,  I divided  the  spinal  marrow 
at  the  occiput  without  at  all  affecting  the  heart. 

Mr.  Clift,  in  an  account  of  experiments  on  the 


108 


carp,  published  in  the  Philosophical  Transac- 
tions for  1815,  observes,  that  on  dividing  the 
spinal  marrow  at  the  occiput,  the  action  of  the 
heart  was  greatly  accelerated  for  a few  beats ; 
but  he  divided  the  spinal  marrow  while  the  ani- 
mal retained  the  power  of  the  muscles  of  volun- 
tary motion,  which  never  fail  to  be  called  into 
action  by  wounding  it,  and  whose  action,  by  in- 
creasing the  flow  of  blood,  always  accelerates  the 
motion  of  the  heart.* 

Thus  we  see  that  neither  chemical  nor  me- 
chanical stimuli  applied  to  the  brain  and  spinal 
marrow,  affect  the  action  of  the  heart,  unless  they 
make  their  impression  on  a large  portion  of  these 
organs.  In  the  various  experiments  I have  re- 
lated, every  part  of  them  was  stimulated  indi- 
vidually, without  the  action  of  the  heart  being  in- 
fluenced ; and  the  stimulus  being  the  same,  the 
force  with  which  it  acted  on  this  organ  was  al- 
ways proportioned  to  the  extent  of  surface  to 
which  it  was  applied.  I could  not  find  that  it 
was  of  any  importance  what  part  of  the  brain 

* It  is  particularly  satisfactory  to  me  that  Mr.  Clift,  on 
repeating  my  experiment,  in  which  the  spinal  marrow  was 
destroyed  by  a hot  wire,  found  the  same  result  in  the  carp, 
which  I had  done  in  rabbits  and  frogs.  He  did  not  ascer- 
tain whether  the  circulation  continued  after  the  destruction 
of  the  spinal  marrow,  but  from  this  occasioning  little  or  no 
diminution  in  the  action  of  the  heart,  we  can  have  little 
doubt  of  the  continuance  of  the  circulation. 


109 


was  stimulated.  Even  stimulating  the  surface 
alone,  either  mechanically  or  chemically,  we  have 
seen,  immediately  increased  the  action  of  the 
heart.  The  muscles  of  voluntary  motion,  on  the 
contrary,  it  appears  from  the  above  experiments, 
are  wholly  insensible  to  stimuli  applied  to  the 
brain,  except  near  the  origin  of  the  nerves  and 
spinal  marrow.  It  is  remarkable  that  while  a 
rabbit  perfectly  retains  its  sensibility,  and  ex- 
presses great  pain  on  any  of  the  muscles  being 
wounded,  it  exhibits  no  expression  of  pain  from 
the  brain  being  sliced,  until  the  knife  approaches 
the  origin  of  the  nerves  or  spinal  marrow. 

Another  circumstance,  which  appears  to  be  of 
great  importance  in  tracing  the  cause  of  the  dif- 
ferent effects  of  stimuli  applied  to  the  brain  and 
spinal  marrow  on  the  muscles  of  voluntary  and 
involuntary  motion,  is,  that  the  heart  obeys  a 
much  less  powerful  stimulus  than  the  muscles  of 
voluntary  motion  do.  We  have  seen  that  only 
the  most  powerful  chemical  stimulus  affects  them, 
while  all  that  were  tried  readily  influenced  the 
action  of  the  heart.  Mechanical  stimuli  which, 
by  bruising  and  dividing  the  parts,  occasion  the 
greatest  possible  irritation,  are  best  fitted  to  ex- 
cite the  muscles  of  voluntary  motion.  Chemical 
stimuli,  indeed,  from  their  effects  on  the  heart,, 
we  should  consider  the  most  powerful.  But  their 
greater  effect  on  this  organ  is  readily  explained 
by  the  influence  of  stimuli  applied  to  the  brain 


110 


and  spinal  marrow  on  the  heart,  being  propor- 
tioned to  the  extent  of  surface  to  which  they  are 
applied.  It  is  evident  that  the  stimulus  can  be 
applied  to  a greater  extent  of  surface  in  the  fluid 
than  in  the  solid  form.  When  the  effect  of  the 
mechanical  agent  is  rendered  extreme,  we  find 
its  influence  on  the  heart  far  greater  than  that  of 
any  chemical  agent  I tried.  From  experiments 
related  in  the  second  chapter  of  this  part,  it  ap- 
pears, that  suddenly  crushing  any  considerable 
portion  of  the  brain  or  spinal  marrow  instantly 
destroys  the  power  of  the  heart. 

The  conclusions  then  at  which  we  arrive  are, 
that  the  heart  is  excited  by  all  stimuli  applied  to 
any  considerable  part  of  the  brain  or  spinal  mar- 
row, while  the  muscles  of  voluntary  motion  are 
only  excited  by  intense  stimuli  applied  to  certain 
small  parts  of  them. 

These  facts  being  ascertained,  the  other  differ- 
ences observed  in  the  effects  of  stimuli  applied  to 
the  brain  and  spinal  marrow,  on  the  heart  and 
muscles  of  voluntary  motion,  are  easily  ex- 
plained. 

Irregular  action  of  a muscle  arises  from  sti- 
muli acting  partially,  or  at  intervals,  on  its  nerves, 
or  on  the  particular  part  of  the  brain  or  spinal 
•marrow,  from  which  its  nerves  arise.  But  very 
partial  action  of  a stimulus  on  the  brain  and  spi- 
nal marrow,  we  have  just  seen,  is  incapable  of 
exciting  the  heart,  and  while  the  stimulus  is  ap- 


Ill 


plied  to  any  part  of  these  organs,  as  all  parts  of 
them  seem  equally  to  influence  the  heart,  it  can- 
not act  upon  it  interruptedly,  as  an  instrument 
does  on  the  muscles  of  voluntary  motion  when 
it  is  moved  from  place  to  place  in  the  brain. 

When  the  instrument  is  kept  still,  after  it  is  in- 
troduced into  the  brain,  the  action  of  the  muscles 
of  voluntary  motion  often  ceases  ; its  merely  be- 
ing in  contact  with  the  parts  of  the  brain  which 
excite  these  muscles,  not  being  sufficient  to  call 
them  into  action.  As  the  muscles  of  voluntary 
motion  feel  the  impressions  made  on  a very  small 
part  of  the  brain  only,  in  proportion  as  this  part 
is  small,  the  impression  must  be  great  to  affect 
them  ; but  the  heart,  which  is  influenced  through 
all  parts  of  it,  though  not  very  powerfully  through 
any  one,  feels  all  the  impressions  made  on  this 
organ,  provided  they  are  made  on  a sufficiently 
extensive  portion  of  it ; thus,  within  certain  li- 
mits, as  long  as  the  instrument  remains  in  the 
brain,  its  stimulant  effect  on  the  heart  continues. 

It  is  true,  that  although  the  heart  is  only  influ- 
enced by  agents  Applied  to  a large  portion  of  the 
brain,  we  may  conceive  them  so  applied  as  to  pro- 
duce irregular  action  in  it,  and  we  find  that  cer- 
tain irritations  of  the  nervous  system  have  this 
effect.  But  it  is  evident,  that  the  heart  not  being 
subject  to  stimuli  whose  action  is  confined  to  a 
small  portion  of  this  organ,  and  being  equally  af- 
fected through  all  parts  of  it,  must  render  it  much 


112 


less  subject  to  irregular  action;  which  may  be 
one  of  the  final  causes  of  the  heart,  whose  regular 
action  is  of  such  importance  in  the  animal  econo- 
my, being  made  subject  to  the  whole,  and  not  to 
any  one  part  of  the  brain  and  readily  accounts 
for  our  not  being  able  to  produce  irregular  action 
in  it,  in  the  above  experiments. 

What  has  been  said  also  explains  why  those, 
who  have  endeavoured  to  influence  the  heart  by 
stimulating  the  parts  of  the  brain  from  which  its 
nerves  seem  chiefly  to  originate,  have  failed. 
When  indeed  the  source  of  the  nerves  of  the  heart 
is  considered,  it  will  be  found  to  derive  its  nervous 
influence  from  every  part  of  the  nervous  system, 
and  not  very  remarkably  from  any  one  part,  a cir- 
cumstance which  particularly  corresponds  with 
the  result  of  the  foregoing  experiments. 

From  the  same  facts  we  explain,  why  the 
heart  is  stimulated  through  the  brain  and  spinal 
marrow  after  their  power  is  so  far  weakened  as  no 
longer  to  convey  the  effect  of  the  stimulus  to  the 
muscles  of  voluntary  motion.  As  these  obey  sti- 
muli applied  to  only  one  part  of  those  organs,  if 
the  change  in  this  part  is  not  sufficiently  strong 
to  produce  the  effect,  it  cannot  be  assisted  by  any 
other.  Thus  I have  found  by  experiment,  that  a 

* In  the  course  of  this  inquiry  another,  and  apparently 
more  important  reason  will  appear,  why  it  is  necessary  that 
the  heart  should  be  subject  to  the  influence  of  every  part  of 
the  brain  and  spinal  marrow. 


113 


blow  which  affects  the  brain  generally,  without 
materially  injuring  it,  produces  comparatively 
little  effect  on  the  muscles  of  voluntary  motion, 
because  no  one  part  suffers  greatly,  but  it  produces 
a great  effect  on  the  heart,  because  it  feels  the  sum 
of  all  the  impressions.  The  nervous  system, 
therefore,  may  be  so  far  exhausted  as  not  to  ad- 
mit of  the  vivid  impressions  necessary  to  excite 
the  muscles  of  voluntary  motion,  and  yet  capable 
of  those  which  influence  the  heart. 


CHAP.  Y. 

On  the  'principle  on  ichich  the  action  of  the  ves- 
sels of  secretion  depends,  and  the  relation 
which  they  hear  to  the  nervous  system. 

It  not  only  appears  from  the  experiments 
which  have  been  laid  before  the  reader,  that  the 
power  of  the  heart  and  vessels  of  circulation  is 
independent  of  the  nervous  system,  but  that  that 
of  the  muscles  of  voluntary  motion  is  so  likewise, 
and  that  these  like  the  former  are  only  subjected 
to  this  system  in  the  same  way  in  which  they 
are  subjected  to  every  other  agent  that  is  capa- 
ble of  exciting  them.  Thus  we  find,  that  all  the 
moving  powers  of  the  animal  body,  as  far  as  we 
have  hitherto  traced  them,  are  independent  of  the 

17 


114 


nervous  system,  but  that  this  system  is  equally 
capable  of  acting  as  a stimulus  to  them,  although 
in  different  ways,  whether  they  are  subject  to  the 
influence  of  the  will  or  not.  Is  the  power  of  se- 
cretion also  independent  of,  though  influencet^by, 

the  nervous  system?  y 

\ 

SECT.  I. 

On  the  effect  of  withdrawing  the  nervous  in- 
fluence from  secreting  surfaces. 

I was  soon  convinced  that  although  the  pow- 
ers of  circulation  are  independent  of  the  nervous 
system,  those  of  secretion  are  very  far  from  being 
so.  M.  le  Gallois,  in  the  treatise  so  frequently 
alluded  to,  enumerates  many  physiologists  who 
divided  the  eighth  pair  of  nerves ; and  lie  gives 
a minute  account  of  the  consequences  of  their 
division,  particularly  of  those  which  he  himself 
observed  in  rabbits  and  Guinea  pigs.  The  chief 
are,  oppressed  breathing  and  loss  of  power  in 
the  stomach.  Mr.  Brodie  also  gives  an  account 
of  experiments,  in  which  he  divided  the  eighth 
pair  of  nerves  in  dogs,  iu  a paper  published  in 
the  Philosophical  Transactions  for  1814.  But 
the  animals  always  died  of  oppressed  breath- 
ing before  he  could  judge  of  the  effect  on  the 
stomach.  He  proved,  however,  by  another  set 


115 


of  experiments,  that  arsenic  introduced  into  the 
system  after  the  division  of 
nerves,  does  not/produce 
from  the  stomai 
to  do  under  o/dinar 
a similar  result” 

Serves  imm/diaf 
the  stomacl 

The  luu^s  are  affecte^differenth 
the  part  at  which  the  nerve  is  divided:  ‘ If,  in  the 
rabbit,  it  b 3 divided  before  the  inferior  laryngal 
nerve  is  se  it  off,  or^this/nerve  itself  is  divided, 
great  difficulty  of  breathing,  with  a croaking 
noise,  immediately  follows,  arising,  as  M.  le  Gal- 
lois  has  shewn,*  from  the  opening  of  the  glottis 
becoming  much  narrowed  as  soon  as  the  nerve  is 
divided.  If  the  eighth  pair  of  nerves  are  divided 
below  the  place  at  which  they  send  off  this  nerve, 
there  is  little  or  no  dyspnoea  for  some  time.  JfeMr. 
Hastings,  who  watched  the  progress  of  the  flow- 
ing experiments  with  great  care,  observed,  that 
when  the  eighth  pair  of  nerves  <were  divided  be- 
low the  inferior  laryngal  nerve,  the  dyspnoea,  al- 


* M.  le  Gallois  says,  that  the  difficulty  of  breathing  comes 
on  from  dividing  the  recurrent  nerves,  but  Mr.  Hastings, 
who  frequently  performed  the  experiment,  always  found 
that  there  was  little  or  no  dyspnoea  induced  in  the  rabbit  by 
dividing  the  recurrent  nerves.  It  was  when  he  divided  the 
laryngal  nerves  that  the  sudden  dyspnoea,  mentioned  by  M. 
le  Gallois,  took  place. 


116 


though  it  often  came  on  sooner,  was  greatly  in- 
creased by  the  attempts  to  vomit,  Avliich  generally 
happened  almost  immediately  after  eating;  but 
which, Vif  tmQinimal  \^s  not  allowed  to  eat,  fre- 
quently >did  not  occur  hour  and  a half,  or 

two  hours^after  the  divisimr^the  nerves.  The 
dyspnoea  increases,  and.  f^^mimal  seems  at  last 
to  die  ofit.yThe  lungswe  found  after  death  dis- 
tended with  a frothy  flum,  which  fills  the  bronchia 
and  air-cells,  and  prevents  the  lungs  collapsing; 
and  they  are  covered  with  patches  of  a dark  red 
colour,  often  of  great  extent,  which  give  the  ap- 
pearance of  the  vessels  being  greatly  distended 
w ith  blood,  or  of  blood  having  escaped  into  the 
cellular  substance.  They  appear  of  a more  com- 
pact texture  than  healthy  lungs,  and  sink  in 
water.  In  short,  the  fluids  of  the  lungs  no  longer 
undergo  the  proper  change,  but  accumulate  in  the 
bronchia,  air-cells  and  blood  vessels.  As  M.  le 
Gallois’  account  of  the  effects  of  the  division  of 
these  nerves  on  the  stomach  does  not  altogether 
agree  with  that  of  the  authors,  he  quotes,  and  is 
also  in  other  respects  contradictory.  Mr.  Hast- 
ings frequently  repeated  the  experiment  on  rab- 
bits, and  sometimes  with  such  dexterity,  that  the 
animal  lived  about  twenty-six  hours  after  the  ope- 
ration. I had  thus  an  opportunity  of  ascertain- 
ing, that  even  during  this  length  of  time,  although 
the  stomach  was  full  of  food,  (parsley)  no  change 
on  it  had  been  effected.  It  continued  in  the  .same 


117 


state  as  when  it  left  the  mouth,  simply  divided  by 
mastication,  preserving  perfectly  both  its  appear*- 
ance  and  its  smell.  It  was  impossible  to  distin- 
guish it  from  parsley  chopped  small  with  a knife. 

It  occurred  to  me,  that  the  pain  and  irritation 
occasioned  by  the  operation  might,  in  these  ex- 
periments, have  induced  such  a degree  of  disease 
as  to  destroy  the  powers  of  digestion,  independ- 
ently of  any  specific  effect  on  the  stomach.  I 
therefore  requested  Mr.  Hastings  to  perform  the 
experiment  in  the  following  manner. 

Exp.  44.  Two  rabbits  of  about  the  same  age 
were  fed  in  the  same  way.  In  both  the  eighth 
pair  of  nerves  were  laid  bare.  In  the  one  rabbit 
they  were  divided  ; in  the  other,  after  being  rais- 
ed on  a probe,  they  were  replaced  without  injur- 
ing them.  Both  rabbits  were  allowed  to  eat  as 
much  parsley  as  they  chose  after  the  operation. 
When  that  in  which  the  nerves  were  divided 
died,  which  did  not  happen  for  more  than  twenty 
hours  after  the  operation,  the  other  was  killed. 
In  the  former  the  food  was  found  wholly  undi- 
gested ; in  the  latter  the  digestive  process  had 
gone  on  as  usual,  and  the  food  was  found  in  the 
same  state  as  in  a healthy  rabbit. 

The  stomach  is  generally  distended  to  a great- 
er size  tiian  usual  when  the  eighth  pair  of  nerves 
have  been  divided.  This  happened  in  the  pre- 
sent case.  It  is  remarkable,  that  the  oesophagus 
also  is  found  full  of  food,  and  very  much  distend- 


118 


ed.  From  this  circumstance,  and  from  an  experi- 
ment of  M.  le  Gallois,  in  which  one  only  of  the 
eighth  pair  of  nerves  being  divided  in  a Guinea 
pig,  the  animal  survived  several  days,  and  the 
stomach  became  enormously  distended  with  un- 
digested food ; I say,  from  these  circumstances,  it 
occurred  to  me,  that  the  sensation  by  which  an 
animal  judges  when  he  has  received  enough  of 
food,  being  destroyed  by  the  division  of  the 
nerves,  the  animals  had  perhaps  occasioned  over- 
distension of  the  stomach,  and  thus  destroyed  the 
power  of  digestion,  for  they  often  ate  a great  deal 
after  the  operation.  I therefore  requested  Mr. 
Hastings  to  repeat  the  experiment,  allowing  the 
animal  to  eat  as  much  as  he  chose  before  the  ope- 
ration, but  none  after  it. 

Exp.  45.  This  he  did,  but  the  result  was  the 
same.  The  food  with  which  the  rabbit  had  filled 
its  stomach,  just  before  the  division  of  the  nerves, 
remained  wholly  unchanged,  and  it  was  remark- 
able, that  the  oesophagus  was  just  as  much  dis- 
tended with  the  food  as  when  the  animal  had 
eaten  after  the  operation.  This  arises  from  the 
fruitless  efforts  to  vomit,  which  always  come  on 
in  an  hour  or  two  after  the  division  of  the  nerves.* 

* I have  already  mentioned  that  Mr.  Hastings  observed  the 
dyspnoea  greatly  increased  by  the  fruitless  attempts  to  vo- 
mit. As  the  oesophagus  in  the  rabbit  lies  contiguous  to  the 
yielding  part  of  the  trachea,  the  distension  of  the  former  can- 
not fail  to  lessen  the  capacity  of  the  latter. 


119 


It  deserves  notice,  that  although  the  eighth  pair 
of  nerves  have  been  divided,  the  food  is  found 
covered  with  apparently  the  same  semi-fluid 
which  Ave  find  covering  the  food  in  a healthy  sto* 
macli. 

These  experiments  seem  to  leave  no  room  to 
doubt,  that  the  office  of  the  stomach  is  suspended 
by  dividing  the  eighth  pair  of  nerves.  A simi- 
lar observation  applies  to  the  lungs.  In  the 
animal  in  which  the  eighth  pair  of  nerves  were 
merely  raised  on  the  probe,  the  lungs  continued 
perfectly  to  perform  their  office,  and  were  found 
of  a healthy  appearance  after  death.  In  all  the 
instances  in  Avhich  these  nerves  Avere  divided, 
great  dyspnoea,  Ave  have  seen,  soon  came  on, 
and  the  air-cells  and  tubes  were  found  clogged 
with  frothy  mucus. 


SECT.  II. 

On  the  nature  of  the  nervous  influence. 

The  discoverer  of  galvanism,  from  Avhom  it 
takes  its  name,  maintained,  that  it  is  the  gal- 
vanic influence  which  is  conveyed  by  the  nerves, 
and  to  which  we  must  ascribe  the  action  of  the 
muscles ; and  with  many  since  his  time  it  has 


120 


been  a favourite  opinion,  that  the  nervous  influ- 
ence is  allied  to  galvanism,  if  they  are  not  the 
same  thing. 

Nobody  however,  as  far  as  I know,  has  at- 
tempted by  experiments  on  the  living  animal,  to 
ascertain  how  far  galvanism  is  capable  of  per- 
forming the  functions  of  this  influence.  To 
ascertain  whether  it  possesses  such  powers,  it 
is  necessary  to  apply  it  to  the  fluids,  as  nearly 
as  possible  in  the  same  way  in  which  the  ner- 
vous influence  is  applied;  to  try,  for  example, 
whether,  when  the  latter  is  withdrawn  from  a 
secreting  surface,  and  the  secreting  power  thus 
wholly  destroyed,  we  can,  by  galvanism,  restore 
this  power,  and  enable  the  part  to  prepare  the 
same  fluid  which  the  nervous  influence  had 
enabled  it  to  prepare. 

We  have  seen,  that  by  dividing  the  eighth 
pair  of  nerves,  the  pow  er  of  digestion,  and  con- 
sequently the  formation  of  gastric  juice,  is  wholly 
lost,  and  the  secreting  power  of  the  lungs  de- 
ranged. This  appeared  to  me  to  offer  an  excel- 
lent opportunity  of  making  the  experiments  in 
question.  It  is  not  difficult,  by  coating  the  lower 
part  of  the  divided  nerves  w ith  tin  foil;  and  ap- 
plying a small  plate  of  metal  to  the  skin  over 
the  stomach  and  lungs,  to  expose  these  organs, 
by  means  of  a galvanic  trough,  to  any  degree 
of  galvanic  power  which  we  may  judge  proper. 


121 


I explained  my  views  to  Mr.  Hastings,  and  re- 
quested him  to  make  the  following  experiment.* 
JSxp.  46.  The  hair  was  shaved  off  the  skin 
over  the  stomach  of  a young  rabbit,  and  a shilling 
hound  on  it.  The  eighth  pair  of  nerves  were 
then  divided,  and  about  a quarter  of  an  inch  of 
the  lower  part  of  each  coated  w ith  tin  foil.  The 
tin  foil  and  shilling  w ere  connected  with  the  op- 
posite ends  of  a galvanic  trough,  containing  fifty- 
two  four-inch  plates  of  zinc  and  copper,  the  in- 
tervals being  filled  w ith  muriatic  acid  and  water, 
in  the  proportion  of  one  of  acid  to  seven  of  wrater. 
The  galvanic  influence  produced  strong  contrac- 
tion of  the  muscles,  particularly  of  the  fore 
limbs. 

For  five  hours  the  animal  continued  quite  free 
from  the  symptoms  which  follow  the  division  of 
the  eighth  pair  of  nerves  in  rabbits.  It  had  nei- 
ther vomited  nor  been  distressed  with  dyspnoea. 
It  had  not  eaten  any  thing  after  the  nerves  were 
divided.  At  this  time  the  power  of  the  trough 
became  much  weaker,  so  that  it  produced  no  vi- 
sible effect  on  the  muscles.  The  respiration  now 
began  to  be  disordered.  In  a quarter  of  an  hour 
it  became  so  difficult,  that  the  animal  appeared 

* From  my  dislike  to  make  experiments  on  living  animals, 
when  I had  occasion  to  make  such  experiments,  I frequently 
requested  my  friends  to  perform  the  operative  part ; but  I 
have  related  none  the  result  of  which  was  not  observed  by 
myself. 


18 


122 


to  be  dying.  It  was  gasping.  Acid  was  put  in- 
to the  trough  till  the  galvanic  power  became  as 
great  as  at  first.  Soon  after  this  the  animal  ceas- 
ed to  gasp,  and  breathed  with  much  greater  free- 
dom. The  galvanic  process  was  several  times 
discontinued  and  renewed,  so  that  Ave  repeatedly 
saw  the  gasping  and  extreme  dyspnoea  return  on 
discontinuing,  and  disappear  on  renew  ing  it. — 
The  animal  died  in  six  hours  after  the  division 
of  the  nerves. 

On  opening  it  we  found  the  oesophagus  perfect- 
ly natural,  and  no  food  in  it.  The  stomach  was 
not  larger  than  usual.  The  food  had  undergone 
a considerable  change.  The  appearance  and 
smell  of  the  parsley  were  gone.  The  smell  was 
that  of  the  rabbit's  stomach  while  digestion  is 
going  on,  which  is  peculiar.  Both  Mr.  Hast- 
ings and  myself,  avIio  have  been  much  accustom- 
ed to  examine  the  stomach  of  rabbits  under  vari- 
ous circumstances,  thought  that  digestion  Avas 
nearly  as  perfect  as  it  >vould  have  been  in  the 
same  time  in  a healthy  rabbit.  This  rabbit  had 
not  eaten  any  thing  for  tw  elve  hours  till  Avithiu 
three  hours  of  the  experiment ; it  Avas  then  very 
hungry,  and  Avas  alloAved  to  eat  as  much  parsley 
as  it  chose. 

The  membrane  of  the  trachea  was  of  its  natu- 
ral colour,  and  there  Avas  no  fluid  in  it.  The 
ramifications  of  the  bronchia  in  the  left  lung  Avere 
quite  free  from  frothy  mucus.  There  Avas  some 


fluid  in  the  right  lung,  though  it  did  not  appear 
much  gorged,  there  was  one  dark  spot  on  it. — 
The  lungs  collapsed  imperfectly  on  opening  the 
chest.  I requested  Mr.  Hastings  to  make  the 
experiment  in  the  following  manner. 

Exp.  47.  Two  full  grown  rabbits  were  kept 
without  food  for  twelve  hours  : within  half  an 
hour  of  the  experiment,  they  eat  as  much  parsley 
as  rabbits  usually  do  at  one  time.  After  the  hair 
was  shaved  off  the  region  of  the  stomach  in  one  of 
them,  and  a shilling  bound  upon  it,  the  eighth 
pair  of  nerves  were  divided  about  eight  o’clock 
in  the  morning,  and  each  nerve  coated  with  tin 
foil,  to  the  extent  of  half  an  inch.  Difficulty  of 
breathing  was  evident  immediately  after  the  ope- 
ration. It  was  nine  o’clock  before  the  animal 
was  brought  properly  under  the  galvanic  influ- 
ence; till  then  the  respiration  was  very  much 
oppressed  ; it  soon  improved  on  keeping  up  a 
regular  and  gentle  twitching  of  the  muscles  of  the 
chest  and  fore-legs.  It  appeared  to  us,  that  in 
the  preceding  experiment  the  animal  had  been 
exhausted  by  the  galvaniv  influence.  In  this  in- 
stance, we  regulated  its  degree  by  the  effect  it 
produced,  using  the  third,  half,  or  whole  of  the 
trough,  according  to  circumstances,  regarding  a 
gentle  twitching  of  the  fore  legs,  as  the  measure  of 
a due  degree  of  the  galvanic  power.  About  ten 
o’clock  the  breathing  became  very  laborious,  ow- 
ing to  the  trough’s  not  acting  well ; on  increasing 


124 


the  galvanic  power  the  breathing  became  pretty 
free,  although  the  animal  still  made  a croaking 
noise  in  respiration,  which  continued  more  or  less 
till  its  death.  The  cause  of  this  I shall  presently 
explain.  The  breathing  always  began  to  get 
worse  when  the  galvanic  power  became  too  weak 
to  produce  any  twitching  in  the  fore-legs. 

At  eight  o’clock  in  the  evening  the  animal  seem- 
ed very  composed,  and  breathed  with  considera- 
ble freedom,  the  trough  having  acted  regularly 
for  some  hours.  Notwithstanding  it  was  kept  in 
the  lying  position  on  its  side,  it  now  eat  greedily 
some  bits  of  parsley  offered  to  it.  The  same  quan- 
tity was  at  the  same  time  given  to  the  other  rab- 
bit. There  did  not  appear  any  increase  of  the 
difficulty  of  breathing,  nor  any  disposition  to  vo- 
mit after  taking  the  food.  It  was  now  about  twelve 
hours  since  the  nerves  were  divided,  during  which 
there  had  not  been  the  least  disposition  to  vomit. 

At  about  a quarter  past  ten,  that  is  fourteen 
hours  and  a quarter  after  the  nerves  had  been  di- 
vided, the  galvanic  influence  had  become  too  fee- 
ble, and  the  animal  made  one  attempt  to  vomit. 
The  power  of  the  trough  was  increased,  and  no 
further  attempt  to  vomit  took  place.  After  this, 
however,  the  breathing  became  more  laborious, 
and  although  it  gradually  improved  very  much, 
it  could  not  be  brought  to  its  former  state,  the  ani- 
mal continuing  to  gasp  slightly.  About  twelve 
o’clock  it  had  a violent  return  of  dyspnoea,  which, 


425 


from  this  time,  to  a quarter  before  one,  increased 
rapidly.  At  one  the  animal  died,  having  survived 
the  division  of  the  nerves  seventeen  hours.  The 
other  rabbit  was  killed  at  the  same  time. 

The  stomachs  of  both  were  laid  open;  we 
found  that  of  the  rabbit,  in  which  the  nerves 
had  been  divided,  no  more  distended  than  the 
stomach  of  the  other.  The  food  in  it  had  the 
appearance  which  it  has  in  a healthy  stomach 
While  digestion  is  going  on.  The  only  differ- 
ences between  the  contents  of  the  two  stomachs 
were  the  following.  The  food  which  the  healthy 
rabbit  had  taken  during  the  experiment,  was- 
found  in  the  cardiac  portion  of  the  stomach, 
and  digestion  was  going  on  rapidly  in  it,  while 
that,  which  the  other  had  taken  at  the  same 
time,  was  still  in  the  oesophagus,  and  conse- 
quently unchanged.  The  position  this  animal 
had  been  in  was  unfavourable  to  the  food’s 
leaching  the  stomach.  There  was  about  a quar- 
ter of  an  inch  of  the  oesophagus,  between  the 
food  and  the  stomach,  quite  empty.  The  con- 
tents of  the  middle  portion  of  the  two  stomachs 
could  not  be  distinguished  from  each  other,  that 
in  the  pyloric  end  only  differed  in  being  of  a 
firmer  consistence  in  the  healthy  rabbit.  In  both, 
the  contents  of  the  pyloric  end  of  the  stomach 
were  most  digested,  and  in  both,  the  food  had 
equally  lost  the  appearance  and  smell  of  parsley, 
and  acquired  the  smell  peculiar  to  the  stomach 


126 


of  the  rabbit  while  digestion  is  going  on.  The 
food  in  the  duodenum  was  equally  digested  in 
both.  W e have  seen,  that  after  the  eighth  pair 
of  nerves  are  divided,  parsley  will  remain  in  the 
stomach  of  a rabbit  wholly  unchanged  for  six 
and  twenty  hours.  Neither  Mr.  Hastings  nor 
myself  could,  from  any  thing  we  saw  in  the  sto- 
mach of  the  rabbit  which  was  galvanised  in  this 
experiment,  have  doubted  its  being  the  stomach 
of  a healthy  rabbit.  We  here  see  the  influence 
of  the  brain  removed,  that  of  the  galvanic  trough 
substituted  in  its  place,  and  the  result  the  same  as 
if  the  influence  of  the  brain  had  still  continued. 

In  this  rabbit  we  found  the  membrane  of  the 
trachea  of  a very  deep  red  colour,  but  there  was 
not  much  fluid  in  it.  The  lungs  did  not  collapse 
on  opening  the  thorax,  the  air-cells  being  full 
of  a frothy  and  bloody  serum.  The  lungs  were 
externally  of  an  uniform  dark  red  colour.  The 
heart  was  a little  increased  in  size,  and  highly 
vascular.  The  cause  of  the  great  dyspnoea  in 
this  experiment,  and  of  the  croaking  noise,  was, 
that  the  laryngal  nerves  were  injured  by  beiug 
stretched,  in  order  to  divide  the  eighth  pair  as 
near  to  them  as  possible,  to  admit  of  so  large  a 
portion  of  the  former  being  coated.  The  reader 
will  see  from  what  is  said  above,  that  dyspnoea 
and  a croaking  noise  are  the  effects  of  injuring 
the  laryngal  nerves.  We  learn  from  the  state 
of  the  lungs  after  the  division  of  the  eighth  pair 


IS? 


of  nerves*  why  an  animal  cannot  be  long  pre- 
served by  artificial  respiration  after  the  brain  is 
removed.  M.  le  Gallois,  indeed,  observes,  that 
artificial  respiration  produces  the  same  loaded 
state  of  the  lungs.  Throughout  the  whole  of  the 
body  there  wras  a general  increase  of  vascularity. 
This,  as  appeared  from  what  was  observed  in 
ether  cases,  was  the  effect  of  the  galvanic  in- 
fluence. 

In  these  experiments  this  influence  had  been 
directed  chiefly  to  the  "region  of  the  stomach.  In 
order  to  see  the  effect  of  directing  it  more  particu- 
larly to  the  lungs,  I requested  Mr.  Hastings  to 
perform  the  experiment  in  the  following  manner. 

Exp.  48.  A full  grow  n rabbit  was  kept  with- 
out food  for  twelve  hours.  Within  two  hours  of 
the  experiment  it  was  allowed  to  eat  as  much 
parsley  as  it  chose.  The  hair  being  then  shaved 
off  the  skin  of  the  thorax,  it  was  covered  with  tin 
foil,  but  not  so  low  as  the  pit  of  the  stomach.  The 
eighth  pair  of  nerves  were  now  divided  low7er  down 
than  in  the  last  experiment,  and  the  lower  por- 
tion of  both  nerves  coated  w ith  tin  foil  for  about 
a quarter  of  an  inch.  The  laryngal  nerves  were 
not  disturbed,  and  no  croaking  ensued.  It  was 
an  hour  after  the  operation  before  the  galvanic 
influence  was  so  applied  as  to  keep  up  a gentle 
twitching  of  the  muscles  of  the  chest  and  fore- 
legs. This  effect  of  the  galvanism  w as  kept  up 


128 


uniformly  for  five  hours,  during  w hich  time  there 
was  hardly  any  dyspnoea. 

In  about  an  hour  after  this,  an  uniform  effect 
from  the  trough  could  not  be  kept  up  on  account 
' of  the  tin  foil  having  been  torn.  In  the  course  of 
an  hour  the  breathing  became  much  w orse,  and 
we  could  not  again  get  the  tin  foil  generally  ap- 
plied to  the  chest.  It  was  kept  imperfectly  ap- 
plied till  the  death  of  the  animal,  which  happen- 
ed in  about  two  hours  and  a half  after  this  ; that 
is,  about  nine  hours  and  a half  after  the  divi- 
sion of  the  nerves.  It  seemed  to  be  produced  by 
dyspncea.  The  animal  had  shew  n no  tendency 
to  vomit. 

The  lungs  collapsed  on  opening  the  thorax, 
though  not  so  perfectly  as  when  they  are  healthy : 
they  swam  in  water.  The  inner  membrane  of 
the  trachea  was  redder  and  more  vascular  than 
usual.  There  was  no  frothy  mucus  in  it.  The 
bronchial  cells,  near  the  great  division  of  the 
trachea,  were  full  of  mucus  ; but  on  tracing  them 
further,  there  was  very  little,  and  none  at  all  to- 
wards the  surface  of  the  lungs,  which  was  of  a 
deeper  red  than  natural,  but  not  shewing  patches 
of  red,  as  where  the  eighth  pair  of  nerves  are 
divided  without  the  application  of  galvanism. 
The  heart  was  much  more  vascular  than  natural. 
The  same  observation  applies  to  every  part  of 
the  thorax.  The  thoracic  viscera,  in  short,  were 


129 


rather  in  a state  of  high  inflammation,  an  effect 
always  produced  by  a considerable  galvanic  pow- 
er in  the  part  to  which  it  was  directed,  of  which 
the  animal  evidently  died,  than  in  that  in  which 
they  are  found  after  the  division  of  the  eighth  pair 
of  nerves. 

The  stomach  was  larger  than  natural,  and  the 
food  but  little  altered,  retaining  the  colour,  smell, 
and  stringiness  of  the  parsley.  There  was  no 
food  in  the  oesophagus.  It  is  evident  that  the 
stomach,  in  this  experiment,  was  but  little  ex- 
posed to  the  galvanic  influence.  It  was  suffici- 
ently so,  however,  to  prevent  the  vomiting,  and 
to  occasion  more  change  in  the  food  than  happens 
when  the  nerves  are  divided  without  applying 
galvanism. 

The  reader  may  remark,  that  as  the  stomach  is 
here  found  in  a state  intermediate  between  that  of 
this  organ,  when  the  eighth  pair  of  nerves  are  di- 
vided without  the  application  of  galvanism,  and 
when  the  galvanism  is  chiefly  directed  to  it ; so 
the  state  of  the  lungs  in  Exp.  46  and  47  is  in- 
termediate between  what  it  was  in  this  experi- 
ment and  what  it  is  when  the  eighth  pair  of 
nerves  are  divided,  without  the  application  of  this 
power. 

As  the  foregoing  experiments  were  made  on 
a graniverous,  a carniverous  animal  was  chosen 
for  the  subject  of  the  following  experiment,  which 
I requested  Mr.  Sheppard  to  perform.  I may 

19 


130 


observe  that  the  three  preceding  experiments 
were  made  in  the  presence  of  three,  and  the  fol- 
lowing experiment  in  that  of  four  medical  men 
besides  myself. 

Exp.  49.  Two  small  dogs  of  the  same  size 
and  age  were  kept  without  food  for  about  thir- 
teen hours ; they  were  then  permitted  to  eat  as 
much  lean  raw  mutton  as  they  chose.  In  both, 
the  eighth  pair  of  nerves  were  divided  immedi- 
ately after  they  had  taken  the  mutton.  In  one 
of  them  the  nerves  were  coated  with  tin  foil,  as 
they  had  been  in  the  rabbits,  a three  shilling 
piece  having  been  previously  bound  on  the  pit  of 
the  stomach  and  lower  part  of  the  thorax,  after 
the  hair  had  been  shaved  off ; and  galvanism  ap- 
plied as  in  the  foregoing  experiments. 

The  dog  which  was  not  galvanised  was  almost 
immediately  affected  with  dyspnoea,  and  within 
ten  minutes  with  violent  and  repeated  efforts  to 
vomit.  The  other  to  which  the  galvanism  was 
applied  of  sufficient  strength  to  occasion  a very 
gentle  motion  in  the  fore-legs,  but  not  any  im- 
pression of  pain,  breathed  as  free  as  before  the 
division  of  the  nerves,  and  never  made  any  effort 
to  vomit.  The  application  of  the  galvanism  was 
twice  discontinued  for  a few  seconds,  during 
which  the  animal  breathed  very  laboriously,  but 
on  renewing  the  galvanism  the  breathing  imme- 
diately became  free.  This  dog  lived  two  hours 
and  a quarter.  On  opening  the  stomach  after 


131 


death  we  found  the  mutton  half  digested.  It  was 
reduced  to  a soft  pulpy  substance,  in  which  there 
was  little  or  no  appearance  of  muscular  fibre. 
That  part  of  the  mutton  which  lay  in  the  pyloric 
end  of  the  stomach  was  most  digested,  which  is 
always  found  to  be  the  case  in  the  healthy  sto- 
mach, and  affords  the  best  proof  that  digestion 
was  going  on  in  the  usual  way.  The  vessels  in 
some  parts  of  the  stomach,  and  throughout  the 
whole  of  the  small  intestines  were  highly  inject- 
ed, giving  those  parts  a very  florid  appearance. 
The  lungs  were  rather  redder  than  natural,  but 
otherwise  quite  healthy,  collapsing  perfectly  on 
the  thorax  being  opened. 

The  other  dog  was  still  alive  at  the  end  of  four 
hours  after  the  nerves  had  been  divided,  but  so 
weak  that  it  could  not  stand  nor  move  itself  from 
the  place  where  it  lay  on  its  side.  It  was  killed 
at  this  time  by  a blow  on  the  occiput.  The 
mutton,  although  it  had  been  in  its  stomach  so 
much  longer  than  in  the  other  dog,  was  as  firm 
as  when  it  was  swallowed,  and  perfectly  retain- 
ed both  its  red  colour  and  fibrous  appearance,  ex- 
cept, that  on  the  outside  the  bits  seemed  as  if 
they  had  been  dipped  in  hot  water : immediately 
below  the  surface  they  were  quite  red.  The 
lungs  exhibited  the  same  appearances  as  those  of 
rabbits  under  the  same  circumstances.  They 
were  so  congested  that  they  collapsed  very  im» 


132 


perfectly,  and  their  surface  was  covered  with 
patches  of  a dark  red  colour. 

There  was  nothing  in  the  stomach  of  either 
dog  but  the  mutton,  which  was  taken  at  the  com- 
mencement of  the  experiment,  and  no  part  of  it 
had  been  throw  n into  the  oesophagus  of  either. — 
All  present  at  this  and  the  three  preceding  ex- 
periments examined  the  state  of  the  stomach  and 
lungs,  and  expressed  their  entire  satisfaction  in 
the  results. 

Is  it  possible  to  explain  the  results  of  these 
experiments  without  admitting  the  identity  of  the 
nervous  influence  and  galvanism?  We  must  ei- 
ther admit  this,  or  that  there  is  another  power, 
capable  of  performing  the  most  characteristic  and 
complicated  functions  of  the  nervous  system. 

It  is  not  to  be  supposed,  that  we  can,  by  the 
artificial  application  of  galvanism,  direct  it  in  the 
proper  quantity  to  the  proper  parts,  in  such  a 
way  as  not  to  supply  more  to  some,  and  less  to 
others,  than  nature  supplies.  Hence,  in  the  fore- 
going experiments,  inflammatory  affections  and 
violent  action  of  the  muscles  were  frequently  ex- 
cited by  it.  This  difficulty,  which  might  easily 
have  been  foreseen,  and  the  cause  of  which  is  so 
obvious,  cannot  weaken  the  inference  from  the 
perfect  performance  of  the  complicated  functions 
of  the  nervous  system  by  galvanism. 

The  power  of  galvanism  over  the  muscles,  the 


133 


phenomena  of  electric  animals,  the  results  of  ex- 
periments  which  have  been  laid  before  the  reader, 
proving  that  the  nervous  influence  bestows  no 
power  on  the  muscular  fibre,  but  acts  only  as  a 
stimulus  to  it,  the  muscles  being  thrown  into  con- 
traction by  the  formation  of  a circle  of  the  nerves 
and  muscles  of  different  limbs,  a pile  formed  of 
alternate  layers  of  muscle  and  brain  exhibiting 
galvanic  phenomena,  and  the  vast  changes  which 
have  been  effected  by  galvanism  in  the  hands  of 
able  chemists,  seem  all  in  some  degree  to  coun- 
tenance the  opinion  of  the  identity  of  the  nervous 
influence  and  galvanism.  To  which  I may  add, 
that  Sir  Everard  Home,  in  a paper  published  in 
the  Philosophical  Transactions  for  1809,  relates 
some  experiments,  from  which  it  appears,  that 
by  the  power  of  galvanism  albumen  may  be  se- 
parated from  the  serum  of  the  blood,  both  in  the 
solid  and  liquid  form.  This  subject  I shall  more 
than  once  have  occasion  to  resume.  Many  cir- 
cumstances tending  to  influence  our  judgment 
respecting  it,  remain  to  be  mentioned. 


134 


SECTION  III. 

Inferences  from  the  preceding  Sections.  ' 

We  have  seen  it  ascertained  in  the  first  of  the 
preceding  sections,  that  the  extreme  parts  of  the 
sanguiferous  and  nervous  systems  are  connected 
in  a way  very  different  from  that  in  which  these 
systems  are  connected  in  other  parts.  The  heart 
and  vessels  of  circulation,  we  have  seen,  can  per- 
form their  functions  after  the  nervous  influence  is 
withdrawn.  The  power  of  secretion  immediately 
ceases  on  the  interruption  of  this  influence.  We 
must  suppose,  therefore,  either  that  the  nervous 
influence  bestows  on  the  extreme  vessels  the 
power  of  separating  and  recombining  the  ele- 
mentary parts  of  the  blood,  or  that  the  vessels 
only  convey  the  fluids  to  be  operated  upon  by 
this  influence. 

It  appears  from  experiments  related  in  the 
second  chapter  of  the  present  part  of  this  In- 
quiry, that  the  most  minute  vessels  which  can 
be  seen  by  a powerful  microscope  in  the  web  of 
a frog’s  foot,  are  independent  of  the  nervous  sys- 
tem. The  motion  of  the  blood  is  as  rapid,  and 
the  circulation  in  the  foot  presents  precisely  the 
same  appearance  after,  as  before  the  destruction 
of  this  system.  Is  it  consistent  with  these  expe- 
riments to  suppose  that  any  part  of  the  sanguifer- 


135 


ous,  derives  its  power  from  the  nervous  system? 
If  the  power  of  the  vessels  of  secretion  had  been 
lost  by  the  destruction  of  the  nervous  system, 
would  it  not  have  occasioned  some  change  in 
the  distribution  and  motion  of  the  blood  in  the 
web  ? The  conclusion  from  these  experiments 
is  strengthened  by  other  facts.  In  those  expe- 
riments in  which  the  power  of  secretion  was 
destroyed  by  withdrawing  the  nervous  influence, 
there  appeared  to  be  no  defective  supply  of  fluids. 
Both  in  the  stomach  and  in  the  lungs  they  were 
sufficiently  copious.  The  fault  seemed  to  be, 
that  a due  change  on  them  had  not  been  effected. 
We  have  no  reason  to  believe,  as  far  as  I am 
capable  of  judging,  that  the  vessels  possess  any 
other  than  a muscular  power,  if  we  except  the 
mere  power  of  elasticity.*  Now  we  have  seen 

* I do  not  mean  here  to  enter  on  the  arguments  which 
seem  to  prove  that  the  power  of  the  vessels  is,  strictly  speak- 
ing, a muscular  power.  For  this  subject  I refer  the  reader 
to  the  observations  of  Mr.  Hunter.  (See  his  work,  intituled 
a Treatise  on  the  Blood,  Inflammation,  and  Gun-shot 
Wounds.)  In  some  animals  the  muscular  structure  of  the 
vessels  is  apparent  on  the  slightest  view.  In  man  and 
animals  resembling  him  it  is  very  obscure,  the  reason  of 
which  Mr.  Hunter  has  pointed  out.  In  them  the  proportion 
of  the  muscular  to  the  elastic  coat  of  the  vessels  is  inversely 
as  the  size  of  the  vessels,  so  that  in  the  larger  vessels  there 
is  comparatively  little  muscular  fibre,  and  in  the  vessels 
possessing  a larger  proportion  of  it,  the  parts  are  too  minute 
to  enable  us  to  detect  it.  The  arguments  of  Mr.  Hunter 


136 


it  proved  by  direct  experiment,  that  the  muscular 
power  throughout  the  whole  animal,  namely,  in 
the  muscles  of  voluntary  motion,  the  heart  and 
the  vessels  of  circulation,  is  independent  of  the 
nervous  system.  Can  we  suppose  that  the  ves- 
sels of  secretion,  which  are  only  a continuation 
of  those  of  circulation,  all  at  once  assume  a dif- 
ferent nature?  Or,  is  it  at  all  consistent  with 
our  knowledge  of  the  phenomena  of  chemistry,  to 
conceive  that,  by  any  influence,  the  muscular 
power  can  be  enabled  to  separate  and  recombine 
the  elementary  parts  of  the  blood  ? The  first  of 
the  above  positions  therefore  may,  I think,  be  re- 
garded as  set  aside.  This  admitted,  does  it  not 
seem  a necessary  inference  from  the  preceding 
experiments  and  observations,  that  in  the  func- 
tion of  secretion  the  vessels  only  convey  the 
fluids  to  be  operated  upon  by  the  nervous  influ- 
ence? If  the  identity  of  the  nervous  influence 
and  galvanism  be  admitted,  we  shall  find  in  the 
known  powers  of  this  agent  a strong  argument  in 
favour  of  the  same  opinion.  We  see  galvanism 
in  a thousand  instances  effecting  changes  of  the 

are  surely  much  strengthened  by  the  foregoing  experiments, 
which  shew  that  the  laws  which  regulate  the  power  of  the 
vessels  of  circulation  are  the  same  with  those  which  regulate 
that  of  the  heart,  whose  muscularity  cannot  be  questioned. 
The  experiments  of  Burzelius  and  Dr.  Young  afford  the 
strongest  argument  against  the  muscularity  of  vessels  by 
showing  that  fibrine  is  not  discoverable  in  their  coats. 


137 


same  kind.  In  the  experiments  related  by  Sir 
Everard  Home,  we  see  it  causing  a separation  of 
albumen,  both  in  the  solid  and  liquid  form,  from 
the  serum,  where  no  vessel^  existed. 

Thus  we  have  every  reason  to  believe,  that  the 
vessels  of  secretion,  like  those  of  circulation,  are 
independent  of  the  nervous  system ; secretion 
failing  when  the  influence  of  this  system  is  with- 
drawn, not  because  the  "vessels  of  secretion  fail  to 
perform  their  office,  but  because  the  necessary 
changes  on  the  fluids  which  they  supply,  no 
longer  take  place. 

We  know  that  the  nervous  power  occasionally 
influences  the  vessels  of  secretion,  as  we  have 
seen  it  does  those  of  circulation,  because  affec- 
tions of  the  mind  frequently  occasion  an  increas- 
ed flow  of  fluids  to  secreting  surfaces.  The  ves- 
sels of  secretion,  therefore,  obey  the  same  laws 
as  those  of  circulation.  They  are  independent 
of,  but  influenced  by,  the  nervous  power.  This 
subject  I shall  have  occasion  to  resume,  in  speak- 
ing of  the  manner  in  which  the  nervous  power  is 
supplied  to  the  sanguiferous  system. 

It  is  not  to  be  overlooked,  that  the  vessels  con- 
vey the  fluids  to  be  operated  upon  by  the  extreme 
parts  of  the  nervous  system,  in  a peculiar  way. 
By  the  lessening  capacities  of  the  capillary  ves- 
sels, the  blood  is  divided  as  by  a fine  strainer, 
some  of  its  parts  being  too  gross  to  enter  the  small- 
er vessels.  How  far  the  blood  may  thus  be  sub- 

30 


138 


divided,  we  cannot  tell.  As  this  structure  of  the 
vessels  is  uniform,  we  have  reason  to  believe  that 
its  effect  on  the  blood  is  necessary  to  prepare  this 
fluid  for  the  due  action  of  the  nervous  influence. 


CHAP.  VI.  0 

On  the  principle  on  which  the  action  of  the  ali- 
mentary canal  depends;  with  some  observa- 
tions on  an  opinion  of  J\tr.  Hunter. 

In  order  to  ascertain  how  far  the  peristaltic 
motion  of  the  intestines  is  independent  of  the 
brain  and  spinal  marrow,  the  following  experi- 
ments were  made. 

Exp.  50.  A rabbit  was  deprived  of  sensibility 
by  a blow  on  the  occiput.  The  whole  of  the  spi- 
nal marrow  was  then  destroyed  by  a hot  wire. 
On  opening  the  abdomen  we  found  the  peristaltic 
motion  of  the  stomach,  and  small  and  great  intes- 
tines, quite  as  strong  as  when  the  nervous  system 
is  entire,  as  we  ascertained  by  exposing  the  ab- 
dominal viscera  of  other  newly-dead  rabbits. 
This  motion  is  as  strong  ill  the  newly-dead,  as 
in  the  living  animal. 

Exp.  51.  The  spinal  marrow  was  wholly  re- 
moved in  another  rabbit,  also  deprived  of  sensi- 
bility by  a blow  on  the  occiput,  without  at  all  af- 


139 

fecting  the  motion  of  the  stomach  and  intestines. 
The  removal  of  the  brain,  we  found,  produces  as 
little  effect  upon  it,  as  that  of  the  spinal  marrow. 
When  both  were  removed  at  the  same  time  it  re- 
mained unaffected.  It  continues  till  the  parts  be- 
come cold,  so  that  when  the  intestines  exposed  to 
the  air  have  lost  their  power,  that  of  those  beneath 
still  remains. 

It  appears  from  these  experiments,  that  the 
power  of  the  stomach  and  intestines,  like  that  of 
the  heart  and  blood  vessels,  resides  in  themselves, 
and  is  wholly  independent  of  any  influence  de- 
rived from  the  nervous  system. 

Thus  we  still  see  that  the  muscular  fibre,  in 
every  part  in  which  we  have  examined  it,  ap- 
pears to  be  independent  of  this  system. 

Mr.  Hunter,  in  a work  just  referred  to,  has 
proved  the  vitality  of  the  blood,  in  so  clear  and 
convincing  a manner,  that  although  the  preju- 
dices of  his  opponents  may  still  lead  them  to  ob- 
ject to  his  arguments,  it  is  impossible  to  reply  to 
them.  This  doctrine  has  been  slowly  received, 
because  those,  who  have  not  been  in  the  habit  of 
correcting  by  reflection,  the  ideas  received  from 
first  impressions,  constantly  associate  their  ideas 
of  life  with  those  of  sensation  and  voluntary 
power.  To  such,  Mr.  Hunter’s  illustration  of 
his  opinion  by  the  process  of  incubation,  will  be 
the  best  reply.  We  see  nothing  in  the  egg  on  a 
superficial  view  but  glairy  fluids  contained  in 


140 


membranes : the  blood  itself  is  not  more  unlike 
wliat  is  usually  called  life  : yet  who  will  doubt 
the  life  of  an  egg,  when  he  sees  that  if  it  be  mere- 
ly kept  in  the  proper  temperature  for  three  or 
four  weeks,  an  animal  of  the  most  perfect  kind, 
complete  in  all  its  parts,  comes  out  of  it. 

Mr.  Hunter  has  shewn,  by  decisive  experi- 
ments, the  analogy  which  subsists  between  the 
contraction  of  a muscle  and  the  coagulation  of  the 
blood.  The  two  acts  in  many  respects  obey  the 
same  laws.  Now  the  muscular  fibre  is  formed 
chiefly  from  that  part  of  the  blood  which  coagu- 
lates. The  coagulation  of  the  blood  every  one 
will  allow  to  be  independent  of  the  nervous  sys- 
tem. It  takes  place  at  least  as  readily  out  of  the 
body  as  in  it,  and  no  nervous  filaments  pass  into 
the  blood.  In  the  formation  of  this  part  of  the 
blood  into  muscular  fibre  therefore,  it  must  whol- 
ly change  its  laws  if  its  power  now  depends  on 
the  nervous  system  ; and  we  can  hardly  suppose 
that  the  analogies  pointed  out  by  Mr.  Hunter, 
could  in  this  case  have  existed. 

One  of  these  analogies  is  intimately  connected 
with  the  result  of  some  of  the  preceding  experi- 
ments. It  was  shewn  in  the  second  chapter,  that 
the  power  of  the  muscular  fibre  may  be  destroy- 
ed by  the  most  powerful  agents  acting  on  the  ner- 
vous system.  Mr.  Hunter  observes,  that  as  the 
muscles,  in  instantaneous  death  from  passion, 
blows  on  the  stomach,  or  electricity,  do  not  con- 


141 


tract  after  death,  so  the  blood  under  the  same  cir- 
cumstances is  found  not  to  coagulate.  When  the 
latter  fact  is  compared  with  the  experiments  just 
alluded  to,  it  appears  a necessary  conclusion,  that 
the  nervous  influence  is  capable  of  acting  on  the 
blood,  a conclusion  which  must  be  regarded,  I 
think,  as  greatly  in  favour  of  the  identity  of  this 
influence  and  galvanism,  for  if  that  conclusion  be 
correct,  the  nervous  influence  must  be  something 
capable  of  pervading  the  fluid  as  well  as  the  so- 
lid parts  of  the  body.  That  electricity  and  the 
most  powerful  affections  of  the  nervous  system 
produce  the  same  effect,  tends  also  to  support 
this  conclusion.  The  inability  of  the  muscle  to 
contract,  and  of  the  blood  to  coagulate  under  the 
foregoing  circumstances,  Mr.  Hunter  ascribes  to 
the  want  of  strong  action  in  the  muscles  and  blood 
where  death  is  so  sudden.  But  it  appears  from 
experiments  which  have  been  laid  before  the 
reader,  that  strong  action,  previous  to  death, 
tends  to  destroy  the  excitability  of  the  muscles, 
which  is  always  found  to  remain,  as  I have  as- 
certained by  many  experiments,  if  they  have  for 
some  time  previous  to  death  been  at  rest,  unless 
it  is  destroyed  by  the  instantaneous  destruction 
of  the  nervous  power,  as  in  the  cases  just  men- 
tioned. I have  found  that  even  the  presence  of 
opium  in  the  system,  only  exhausts  the  excitabi- 
lity of  the  muscles  in  proportion  to  the  frequency 


142 


and  force  of  the  contractions  it  excites  in  them.* 
Compare  Exp.  19,  20,  21,  and  22,  with  Exp.  31. 

* The  convulsions  excited  by  opium  always  assume  the 
form  of  the  opisthotonos.  The  animal  becomes  rigid  and  is 
bent  backwards.  During  the  intermission  of  these  convul- 
sions the  slightest  touch  renews  them.  If  the  animal  is  al- 
lowed to  remain  undisturbed  they  but  rarely  occur.  By  fre- 
quently touching  it,  a constant  succession  of  them  may  be 
kept  up.  In  the  former  case  the  excitability  ol  the  muscles 
is  little  impaired,  in  the  latter  case  it  is  nearly  exhausted. 

As  I have  frequent  occasion  in  this  Inquiry  to  mention 
the  effects  of  opium  and  tobacco,  I shall  take  the  present 
opportunity  of  laying  before  the  reader  the  result  of  many 
experiments  which  I made  with  a view  to  ascertain  the 
modus  operandi  of  these  drugs  on  the  living  animal. 

It  appears  from  these  experiments  that  their  effects  may 
be  divided  into  thr  ee  classes. 

1st.  Their  effects  on  any  part  of  the  body  to  which  they 
are  immediately  applied.  In  very  small  quantity  they  tend 
to  excite  muscular  action.  In  larger  quantity  they  imme- 
diately destroyed  the  muscular  power.  They  produce  these 
effects  in  the  hollow  muscles,  the  heart,  intestines,  &c. 
chiefly  when  applied  to  their  internal  surfaces.  When  in- 
jected in  considerable  quantity  under  the  skin,  they  destr  oy 
the  circulation  in  the  part  by  destroying  the  power  of  its 
vessels.  By  their  operation  on  the  nerves  of  the  part,  when 
applied  in  small  quantity,  they  produce  a degree  of  excite- 
ment in  the  whole  nervous  system,  and,  through  it,  in  tire 
sanguiferous  system.  In  large  quantity,  especially  when 
applied  to  a very  sensible  and  extensive  surface,  they  pro- 
duce to  a greater  or  less  degree  an  immediate  torpor  of  the 
nervous,  and,  through  it,  of  the  sanguiferous  system.  In  all 
these  instances  the  stimulant  effect  of  the  opium  is  more 


143 


Of  the  physiologists,  either  of  our  own  or  for- 
mer times,  none  ranks  higher  than  Mr.  Hunter. 

considerable  than  that  of  the  tobacco,  and  the  sedative 
effect  of  the  latter  is  more  considerable  than  that  of  the 
former. 

The  second  class  of  the  effects  of  opium  and  tobacco  are 
those  they  produce  on  the  sanguiferous  system,  in  conse- 
quence of  their  absorption.  These  effects  begin  in  about 
a quarter  of  an  hour  or  twenty  minutes  after  they  are  re- 
ceived into  the  stomach  and  intestines,  and  appear  to  be 
precisely  the  same  as  the  effects  of  opium  and  tobacco  when 
immediately  applied  in  small  quantity  to  the  heart  and  blood 
vessels ; but  here  they  are  complicated  with  the  third  class, 
into  which  I would  divide  the  effects  of  these  drugs  on  the 
living  animal,  namely  their  effects  on  the  brain. 

These  are,  some  degree  of  excitement,  most  remarkable 
when  opium  is  used,  followed,  except  the  quantity  be  very 
small,  by  languor  and  an  inclination  to  sleep,  the  former 
most  considerable  from  tobacco,  the  latter  from  opium ; and 
if  the  quantity  be  great,  by  general  convulsions  of  the  kind 
just  described  when  opium  has  been  used,  and  when  to- 
bacco has  been  used,  by  tremblings  and  paralysis.  I have 
made  many  experiments  to  ascertain  whether  the  last  effects 
can  arise  from  the  action  of  opium  and  tobacco  on  any  other 
part  than  the  brain,  and  have  found  that  they  never  arise 
from  the  action  of  those  drugs  on  any  other  part.  It  has 
been  maintained  by  Dr.  Monro  and  others,  that  convulsions 
arise  from  the  action  of  opium  on  the  nerves  of  the  heart, 
because  they  found  that  on  injecting  an  infusion  of  opium 
into  the  heart,  convulsions  very  quickly  ensue.  But  this 
only  happens  in  consequence  of  the  infusion  passing  along 
the  aorta  to  the  brain,  for  if  the  aorta  be  secured  by  ligature 
no  convulsions  take  place.  The  same  observations,  I have 
found  by  experiments  frequently  repeated,  apply  to  the 


144 


In  originality  he  has  perhaps  had  no  equal : yet 
I have  hitherto  had  little  occasion  to  mention  his 
name,  and  in  the  Report  of  the  National  Insti- 
tute of  France,  which  has  been  laid  before  the 
reader,  his  name  is  not  mentioned  at  all.  This, 
which  seems  at  first  view  to  throw  some  reflec- 
tion on  the  importance  of  Mr.  Hunter’s  labours, 
is  in  fact  his  highest  praise.  It  arises  from  his 
having,  in  his  principal  physiological  investiga- 
tions, struck  into  a wholly  new  field  of  inquiry ; 
so  that  in  examining  the  opinions  of  others,  we 
are  hardly  led  to  any  mention  of  his.  The  same 
circumstance  has  occasioned  his  opinions  to  be 

tremblings  and  paralysis  produced  by  tobacco.  Now  as 
these  effects  of  tobacco,  and  the  convulsions  produced  by 
opium,  always  sooner  or  later  ensue  to  whatever  parts  of 
the  body  they  are  applied,  the  experiments  above  alluded  to 
prove  that  they  are  received  into  the  system  by  means  of 
the  absorbents.  It  would  enlarge  this  note  to  the  size  of  a 
treatise  to  give  a detail  of  all  the  experiments  from  which 
the  above  inferences  were  drawn,  for  the  present  therefore 
I must  beg  the  reader  to  believe  that  they  were  performed 
with  all  requisite  care.  No  inference  was  drawn  from  any 
experiment  till  it  had  been  frequently  repeated  with  the 
same  result.  Many  of  these  experiments  were  detailed  in 
an  appendix  to  the  third  volume  of  the  second  edition  of 
my  Treatise  on  Febrile  Diseases.  This  and  another  ap- 
pendix, being  a set  of  experiments  made  with  a view  to 
ascertain  the  circumstances  in  diet  which  influence  the 
spontaneous  depositions  from  the  urine,  were  omitted  in 
the  last  edition,  in  order  that  the  work  might  be  comprised 
in  two  volumes. 


145 


bat  little  known  abroad.  While  the  attention 
of  physiologists  was  chiefly  directed  to  ascertain 
the  nature  of  that  power  on  which  muscular  action 
depends,  and  the  relation  of  the  muscular  and 
nervous  systems,  and  while  in  these  subjects 
there  were  still  ample  fields  of  dispute,  they 
were  not  likely  to  be  diverted  from  them  to  in- 
quiries, apparently  unconnected  with  their  fa- 
vourite objects. 

Previous  to  Mr.  Hunter,  the  physiologists  of 
this  country  joined  their  endeavours  to  those  of 
the  continent  in  the  above  researches.  From  his 
childhood  he  was  averse  to  the  restraints  of  edu- 
cation, and  he  at  no  time  bestowed  much  pains 
on  acquiring  a knowledge  of  the  opinions  of 
others.  In  the  volume  of  nature  he  found  the 
work  best  suited  to  his  taste.  It  lay  open  before 
him,  and  uninfluenced  by  the  habits  of  his  prede- 
cessors, it  was  not  surprising  that  he  should  turn 
to  a page  different  from  that  on  which  they  had 
dwelt  so  long.  Thus  he  gave  a new  turn  to  the 
pursuits  of  British  physiologists,  which  has  ever 
since  distinguished  them  from  those  of  the  con- 
tinent. While  the  latter  were  occupied  in  en- 
deavouring to  establish  or  refute  the  opinions  of 
Haller,  and  to  add  to  the  valuable  facts  ascer- 
tained respecting  the  subjects  of  these  disputes  ; 
the  former  have  in  the  same  way  been  engaged 
in  endeavouring  to  support  or  refute  the  opinions 
of  Mr.  Hunter,  and  to  extend  our  knowledge  of 

31 


146 

the  subjects  to  which  he  had  directed  his  atten- 
tion. 

The  advancement  of  knowledge  will  necessa- 
rily draw  together  these  different  sects  of  physio- 
logists, and  the  objects  of  their  pursuit  will  at 
length  become  the  same.  As  they  acquire  a more 
perfect  knowledge  of  the  animal  (economy,  each 
sect  will  perceive  that  the  discoveries  of  the  other 
are  necessary  for  the  advancement  of  their  own, 
and  the  endeavours  of  all  will  thus  be  directed  to 
one  end.  Mr.  Hunter’s  name,  we  may  venture 
to  predict,  will  then  stand  as  high  in  other  coun- 
tries as  it  does  in  his  own.  I do  not  mean  to  say 
with  the  blind  admirers  of  Mr.  Hunter,  that  we 
know  nothing  but  what  he  has  taught  us,  and 
that  foreign  physiologists  might  have  learnt  from 
Mr.  Hunter  what  they  have  learned  from  their 
own  labours.  He  has  not  laboured  in  the  same 
field  with  them,  he  has  broken  new  ground,  in 
the  cultivation  of  which  they  will  join : he  has 
opened  new  views,  for  which  they  will  make 
their  acknowledgements,  as  soon  as  the  determi- 
nation of  the  questions,  by  which  they  have  been 
so  long  occupied,  gives  them  leisure  to  view  what 
he  has  done  in  another  and  not  less  important 
part  of  the  same  subject.  * 

* I say  nothing  here  of  the  great  pathological  labours  of 
this  acute  observer.  There  are  two  peculiarities  of  Mr. 
Hunter’s  writings,  which  will  tend  to  prevent  their  becoming 
popular  with  foreigners;  an  occasional  obscurity  of  style, 


1W 


We  are  now  to  inquire  whether  the  alimenta- 
ry canal,  like  the  heart  and  blood  vessels,  is  ca- 
pable of  being  stimulated  through  the  nervous 
system. 


CHAP.  VII. 

On  the  relation  which  the  alimentary  canal  bears 
to  the  nervous  system. 

The  alimentary  canal  is  of  such  importance  in 
the  animal  (Economy,  that  it  is  of  the  first  conse- 
quence in  tracing  the  laws  of  the  vital  functions 
to  ascertain  the  principle  on  which  its  action  de- 
pends, and  the  relation  which  subsists  between 
it  and  the  nervous  system ; the  former  of  these 
points  I have  endeavoured  to  ascertain  by  the  ex- 
periments related  in  the  preceding  chapter,  the 
latter  we  are  now  to  consider. 

and  a degree  of  refinement  which  often  loses  sight  of  all  cor- 
rect rules  of  reasoning ; an  example  of  the  latter  we  have 
in  his  doctrine  of  the  stimulus  of  necessity. 

The  reader  will  not  be  surprised  to  find  in  the  works  of 
Mr.  Hunter,  repetitions  and  other  marks  of  their  often  hav- 
ing been  composed  in  haste,  and  under  the  pressure  of  many 
engagements.  These,  while  they  lessen  the  accuracy  of  the 
works,  tend  perhaps  rather  to  raise  our  opinion  of  their  au- 
thor, for  he  is  never  betrayed  into  a neglect  of  the  great  lines 
of  his  subject,  or  inaccuracies  of  consequence. 


148 


Exp.  52.  I endeavoured  to  ascertain  how  far 
the  motion  of  this  canal  is  influenced  by  stimuli 
applied  to  the  brain  and  spinal  marrow ; but  from 
its  nature  it  is  in  every  way  so  irregular  that  no 
certain  result  could  be  obtained.  It  often  appear- 
ed that  spirit  of  wine  applied  to  the  brain  and 
spinal  marrow  increased  it. 

The  admission  of  air  into  the  cavity  of  the  ab- 
domen throws  the  bowels  into  strong  spasmodic 
action,  which  alone  would  obscure  any  effect  that 
can  be  supposed  to  arise  from  stimulating  the 
brain.  The  abdomen  was  therefore  opened  un- 
der tepid  water,  but  this  was  found  to  excite  even 
stronger  spasms  than  the  air  had  done.  The  ef- 
fects of  the  passions  on  the  alimentary  canal,  how- 
ever, leave  no  room  to  doubt  that  it  is  capable  of 
being  stimulated  through  the  nervous  system.  It 
remains  to  be  ascertained  whether  it  is  subject 
only  to  certain  parts  of  the  brain,  or,  like  the 
heart,  to  every  part  of  that  organ  and  of  the  spi- 
nal marrow. 

It  is  evident,  from  the  circumstances  just  men- 
tioned, that  it  is  impossible  to  answer  this  ques- 
tion respecting  the  alimentary  canal,  as  respect- 
ing the  heart,  by  agents  applied  to  different  parts 
of  the  brain  and  spinal  marrow.  Before  I relate 
the  experiments  which  I had  recourse  to  for  this 
purpose,  I shall  make  some  observations  on  the 
process  of  digestion  in  the  animal  on  which  these 
experiments  were  made,  which  will  place  in  a 


149 


clearer  point  of  view  both  their  results,  and  those 
of  some  experiments  which  have  been  laid  before 
the  reader. 

SECT.  I. 

On  the  'process  of  Digestion. 

On  the  functions  of  the  stomach  all  other  func- 
tions of  the  animal  body  may  be  said  to  depend, 
as  their  various  organs  derive  from  it  that  supply, 
without  which  they  can  exist  only  for  a very  short 
time.  In  another  point  of  view  we  find  the  sto- 
mach equally  important.  There  is  no  other  or- 
gan whose  diseases  are  at  once  so  frequent  and 
so  varied,  or  which  partakes  more,  perhaps  so 
much,  of  the  diseases  of  other  parts,  or  of  the 
whole  system. 

It  is  not  however  my  intention  to  enter  fully 
into  that  part  of  the  process  of  digestion  which  is 
performed  in  the  stomach.  The  experiments  of 
Spalanzani  and  others  sufficiently  prove  that  the 
change  which  the  food  undergoes  in  this  organ  is 
effected  by  a fluid  secreted  by  it.  I shall  con- 
fine myself  to  such  circumstances  attending  this 
change  as  serve  to  elucidate  the  results  of  the  ex- 
periments which  have  been  or  are  about  to  be 
laid  before  the  reader. 

I have  inspected  after  death,  under  various 


150 


circumstances,  and  at  different  periods  after  tak- 
ing food,  the  stomachs  of  about  a hundred  and 
thirty  rabbits,  which  has  enabled  me  not  only  to 
ascertain  some  points  that  will  place  the  result 
of  many  of  my  experiments  in  a clearer  light,  but 
to  observe  more  particularly  thau  has  been  done 
by  others,  the  process  of  digestion  in  this  animal ; 
which,  from  the  ease  with  which  it  can  be  pro- 
cured, and  its  tenacity  of  life,  has  been  so  much 
employed  in  physiological  investigations.  How 
far  the  following  observations  will  apply  to  other 
animals  I cannot  say.  In  carniverous  animals 
the  process  of  digestion  may  be  different,  and  in 
animals  furnished  with  a gizzard,  in  some  respects, 
it  certainly  is  so.  A knowledge  of  this  process 
in  any  one  animal,  however,  must  be  useful  in 
our  attempts  to  trace  it  in  others. 

The  experiments  on  this  part  of  the  subject 
were  so  frequently  repeated,  that  it  would  be  te- 
dious and  unprofitable  to  give  an  account  of  each 
experiment.  I shall  here  therefore,  under  the 
head  experiment,  give  the  result  of  all  the  expe- 
riments on  each  particular  part  of  the  subject 
Mr.  Sheppard  was  so  good  as  to  assist  me  in 
these  experiments. 

Exp.  53.  The  first  thing  which  strikes  the  eye  . 
on  inspecting  the  stomachs  of  rabbits  which  have 
lately  eaten,  is,  that  the  new  is  never  mixed  with 
the  old  food.  The  former  is  always  found  in  the 
centre,  surrounded  on  all  sides  by  the  old  food. 


151 


except  that  on  the  upper  part,  between  the  new 
food  and  the  smaller  curvature  of  the  stomach, 
there  is  sometimes  little  or  no  old  food.  If,  as 
we  ascertained  by  more  than  twenty  trials,  the 
old  and  the  new  food  are  of  different  kinds,  and 
the  animal  is  killed  after  taking  the  latter,  unless 
a great  length  of  time  has  elapsed  after  taking  it, 
the  line  of  separation  is  perfectly  evident,  so  that 
all  the  old  may  be  removed  without  disturbing 
the  new  food.  For  this  purpose  we  fed  rabbits 
on  oats,  and  after  making  them  fast  for  sixteen 
or  seventeen  hours,  allowed  them  to  eat  as  much 
cabbage  as  they  chose,  and  killed  them  at  differ- 
ent periods,  from  one  to  eight  hours  after  they  had 
eaten  it. 

On  opening  the  stomachs  of  rabbits  three  or 
four  weeks  old,  who  both  sucked  and  eat  green 
food,  we  always  found  the  curdled  milk  unmixed 
with  the  green  food.  Before  the  stomach  was 
opened  we  could,  from  its  transparency,  see 
where  the  green  food  and  where  the  milk  lay. 
The  rabbits  used  in  this  and  all  the  experiments 
which  I am  about  to  relate  in  this  section,  were 
killed  by  a blow  on  the  occiput. 

Exp.  54.  If  the  old  and  the  new  food  be  of 
the  same  kind,  and  the  animal  is  allowed  to  live 
for  a considerable  time  after  taking  the  latter,  the 
gastric  juice,  passing  from  the  old  to  the  new 
food,  and  changing  as  it  pervades  it,  renders  the 
line  of  separation  indistinct ; but  towards  the 


1 52 


small  curvature  of  the  stomach,  and  still  more  to- 
wards  the  centre  of  the  new  food,  we  find  it,  un- 
less it  has  been  very  long  in  the  stomach,  com- 
paratively fresh  and  undisturbed.  All  around, 
the  nearer  the  food  lies  to  the  surface  of  the  sto- 
mach, the  more  it  is  digested.  This  is  true  even 
with  regard  to  the  small  curvature  compared  with 
the  food  near  the  centre,  and  the  food  which 
touches  the  surface  of  the  stomach  is  always  more 
digested  than  any  other  found  in  the  same  part  of 
the  stomach.  But  unless  the  animal  has  not  eat- 
en for  a great  length  of  time,  it  is  in  very  differ- 
ent stages  of  digestion  in  different  parts  of  the 
stomach.  It  is  least  digested  in  the  small  curva- 
ture, more  in  the  large  end,  and  still  more  in  the 
middle  of  the  great  curvature. 

These  observations  apply  to  the  cardiac  por- 
tion of  the  stomach.  Sir  Everard  Home,  in  his 
work  on  Comparative  Anatomy,  has  shewn  that 
the  stomach  is  divided  into  two  portions,  the  car- 
diac and  pyloric,  in  such  a way,  that  the  length 
of  the  former  is  to  that  of  the  latter  nearly  as  two 
to  one.  The  line  of  division  may  generally  be 
seen  in  some  animals  after  death.  He  says  it  is 
more  evident  while  digestion  is  going  on.  I have 
sometimes  observed  it  very  distinctly  after  death 
in  the  stomach  of  the  rabbit,  and  have  then  found 
the  food  in  the  two  cavities  divided  by  an  evident 
line  of  separation  as  described  by  this  author. 
These  two  portions  of  the  stomach  form  an  an 


153 


gle  with  each  other,  which  is  well  expressed  by 
the  plates  in  Sir  Everard  Home’s  work. 

Exp.  55.  The  food  in  the  pyloric  portion  of 
the  stomach  of  the  rabbit,  is  always  found  in  a 
state  very  different  from  that  just  described.  It 
is  more  equally  digested,  the  central  parts  dif- 
fering less  in  this  respect  from  those  which  lie 
next  the  surface  of  the  stomach;  it  is  evident, 
however,  that  all  the  change  effected  in  the  sto- 
mach is  not  completed  when  the  food  enters  this 
portion  of  it,  because  we  find  it  the  more  digested 
the  nearer  it  approaches  to  the  pylorus,  where 
being  ready  to  pass  into  the  intestine,  it  has  un- 
dergone all  that  part  of  digestion  which  is  per- 
formed in  the  stomach. 

One  of  the  most  remarkable  differences  be- 
tween the  state  of  the  food  in  the  cardiac  and 
pyloric  portions  of  the  stomach,  is,  that  in  the 
latter  it  is  comparatively  compact  and  dry,  in  the 
former  mixt  with  a large  proportion  of  fluid,  par- 
ticularly when  digestion  is  pretty  far  advanced, 
and  time  consequently  has  been  given  for  a con- 
siderable secretion  from  the  stomach.  In  the 
rabbit  indeed,  which  is  fed  only  witli  solid  food, 
in  the  early  stage  of  digestion  it  is  nearly  as  free 
from  liquid  in  the  cardiac  as  in  the  pyloric  por- 
tion of  the  stomach.  When  digestion  is  very  far 
advanced,  the  whole  contents  of  the  former  are 
often  reduced  to  the  state  of  a semi-fluid.  But 
even  then  the  food  in  the  pyloric  portion,  par- 

22 


154 


ticularly  those  parts  of  it  which  are  near  the 
pylorus,  are  comparatively  compact  and  dry.  In 
rabbits  so  young  as  to  live  wholly  on  milk,  the 
curdled  milk  is  considerably  softer  and  moister 
in  the  cardiac  than  in  the  pyloric  end  of  the  sto- 
mach. An  interesting  question  here  arises,  what 
becomes  of  the  liquid  part  of  the  contents  of  the 
cardiac  portion  of  the  stomach  when  the  solid 
part  is  moved  on  towards  the  pylorus  ? 

This  question  has  particularly  engaged  the 
attention  of  Sir  Everard  Home.  What  first 
suggests  itself  is,  that,  as  the  stomach  is  con- 
stantly secreting  a fresh  supply  of  fluids,  for  the 
purpose  of  digestion,  those  which  have  performed 
their  office,  and  are  no  longer  useful  in  this  ca- 
vity, are  removed  by  absorption,  analogous  to 
what  appears  to  be  constantly  going  on  in  other 
parts  of  the  body.  But  Sir  Everard  Home  re- 
lates several  experiments,  from  which  he  infers 
that  liquids  are  removed  from  the  cardiac  por- 
tion of  the  stomach  by  some  other  means  than 
the  absorbent  system.  What  these  means  are,  he 
found  it  impossible  with  certainty  to  determine. 

Exp.  56.  Although  the  food  is  in  the  most  di- 
gested state  in  the  pyloric  end,  it  appears  from 
several  circumstances  that  the  change  is  chiefly 
effected  in  the  great  end  of  the  stomach.  The 
food  found  in  the  pyloric  end  we  have  just  seen 
is  comparatively  dry,  while  that  found  in  the 
great  end,  if  digestion  is  much  advanced,  is  mix- 


1 55 


cd  copiously  with  the  juices  of  the  stomach,  and 
there  is  a more  evident  difference  in  the  state 
of  the  food  before  it  comes  into  this  part,  and 
when  it  is  about  to  leave  it,  than  in  any  other 
part  of  the  stomach.  I shall  presently  have  oc- 
casion to  mention  a fact  ascertained  by  Mr.  Hun- 
ter, which  seems  to  confirm  this  opinion.  Mr. 
Hastings  on  examining  the  stomach  of  a woman 
who  had  died  under  his  care,  found  it  every 
where  in  a state  of  ulceration,  except  in  the  great 
end,  where  it  was  healthy.  The  stomach  had 
performed  its  functions  to  the  last,  and  the  faeces 
proved  that  the  food  had  been  properly  digested. 

It  appears  that  in  proportion  as  the  food  is 
digested,  it  is  moved  along  the  great  curvature, 
where  the  change  in  it  is  rendered  more  perfect, 
to  the  pyloric  portion.  Thus,  the  layer  of  food 
lying  next  the  surface  of  the  stomach  is  first  di- 
gested. In  proportion  as  this  undergoes  the  pro- 
per change,  it  is  moved  on  by  the  muscular  ac- 
tion of  the  stomach,  and  that  next  in  turn  suc- 
ceeds to  undergo  the  same  change.  As  the  gas- 
tric juice  pervades  the  contents  of  the  stomach, 
though  apparently  in  no  other  way  than  by  sim- 
ple juxtaposition,  for  the  arrangement  of  the 
food  above  described,  we  never  found  disturbed, 
the  change  in  each  part,  which  in  its  turn  comes 
in  contact  with  the  stomach,  is  far  advanced  be- 
fore it  is  in  actual  contact  with  it;  and  conse- 
quently is  soon  after  this  in  a proper  state  to  be 


156 


moved  on  towards  the  pyloric  end.  Thus  a con- 
tinual motion  is  going  on,  that  part  of  the  food 
which  lies  next  the  surface  of  the  stomach  pass- 
ing towards  the  pylorus,  and  the  more  central 
parts  approaching  the  surface.  Whether  food  is 
ever  so  digested  in  the  small  curvature,  as  to  be 
sent  to  the  pyloric  portion,  without  having  tra- 
versed the  large  curvature,  I have  not  been  able 
to  ascertain.  When  rabbits  have  fasted  six- 
teen or  eighteen  hours,  the  whole  food  found  in 
the  cardiac  portion,  which  is  in  small  quantity 
compared  to  what  is  found  in  it  immediately  af- 
ter a full  meal,  seems  frequently  to  be  all  nearly 
in  the  same  state  with  that  next  its  surface,  the 
gastric  juice  having  pervaded  and  acted  upon 
the  whole,  and  is  consequently  apparently  fitted 
to  be  sent  to  the  pyloric  end.  Sir  Everard  Home 
found  that  the  stomach  of  a rabbit  never  empties 
itself,  containing  even  when  the  animal  dies  after 
long  fasting,  a considerable  quantity  of  food. — 
The  first  impression  on  the  food  is  made  in  the 
small  curvature,  because  the  upper  part  of  the 
new  food,  which  lies  contiguous  with  this  part  of 
the  stomach,  or  nearly  so,  is  always  found  more 
changed  than  the  more  central  parts  of  it. 

We  frequently  found  in  the  large  end  of  the 
stomach  the  small  round  masses  or  balls,  about 
the  size  of  the  largest  kind  of  shot,  mentioned 
by  Sir  Everard  Home.  These  balls  are  very 
constantly  found  in  the  great  end  of  the  stomach 


157 


of  rabbits,  especially  when  fed  on  green  food, 
never  in  any  other  part  of  it.  They  are  often 
very  numerous,  sometimes  forming  the  whole 
contents  of  that  part  of  the  stomach.  They 
cannot  be  fewer  in  many  cases  than  from  two  to 
four  hundred.  At  other  times  they  are  much  less 
numerous,  and  mixed  with  food  of  the  same  con- 
sistence with  that  of  which  they  are  formed.  It 
is  difficult  at  first  view  to  account  for  their  ap- 
pearance. The  ingenious  idea  of  Sir  Everard 
Home  that  they  are  produced  by  the  rabbit  occa- 
sionally ruminating,  is  opposed  by  several  cir- 
cumstances ; the  frequency  of  their  appearance, 
their  sometimes  forming  one  half  or  more  of  the 
contents  of  the  stomach,  their  being  always  found 
at  a considerable  distance  from  the  opening  of  the 
oesophagus  into  the  stomach  unless  their  number 
is  so  great  as  to  fill  the  greater  part  of  the  sto- 
mach, food  much  less  digested  than  that  compos- 
ing them  generally  lying  between  them  and  this 
orifice,  and  no  appearance  of  this  kind  being 
found  in  ruminating  animals. 

It  was  long  before  I could  form  even  a proba- 
ble conjecture  respecting  the  formation  of  these 
balls.  I have  now,  from  inspecting  many  sto- 
machs containing  them,  very  little  doubt  of  the 
cause  to  which  they  are  to  be  ascribed.  When 
the  stomach  of  the  rabbit  is  laid  open,  the  great 
end  is  found  corrugated  forming  rugae,  which 
give  it  a honey-comb  appearance.  These  rugae 


158 


disappear  when  it  is  stretched,  and  as  soon  as 
the  stretching  power  is  withdrawn,  again  appear, 
the  rest  of  the  stomach  being  comparatively 
smooth.  The  balls  seem  to  be  formed  in  the 
hollows  of  these  rug®,  which  are  about  the  same 
size  with  the  balls.  It  would  appear  that  the 
food  by  the  action  of  this  part  of  the  stomach,  is 
rolled  up  into  these  masses  after  it  has  undergone 
that  part  of  the  digestive  process  Avhich  takes 
place  in  the  great  end  of  the  stomach,  and  conse- 
quently after  it  has  been  exposed  for  a conside- 
rable time  to  the  action  of  the  gastric  juice;  in 
which  form  it  is  sent  towards  the  pyloric  end, 
where  the  balls  are  broken  down,  and  the  whole 
again  formed  into  one  mass  of  a firmer  consist- 
ence than  the  balls.  I have  observed  that  when 
all  the  food  in  the  great  end  of  the  stomach  is  com- 
posed of  these  balls,  it  contains  no  fluid  but  that 
which  is  mixed  up  with  the  food  in  them.  Some- 
times no  balls  are  formed.  This  is  comparatively 
rare.  We  never  found  the  curdled  milk  formed 
into  balls,  consequently  there  are  no  balls  in 
the  stomachs  of  very  young  rabbits.  With  this 
exception  they  are  frequently,  I may  say  very 
generally,  found  under  all  circumstances  of  diet, 
situation,  &c.  Sometimes  when  rabbits  had  lived 
precisely  in  the  same  way,  they  were  not  found 
in  all.  They  are  sometimes  found,  when  the 
more  central  parts  of  the  contents  of  the  stomach 
have  undergone  little  or  no  change. 


159 


Exp.  57.  It  is  in  the  great  end  of  the  stomach 
where  digestion  appears  to  go  on  so  rapidly, 
that  Mr.  Hunter  found  the  stomach  itself  dis- 
solved; and  by  the  most  satisfactory  arguments 
shewed  that  this  is  the  effect  of  the  gastric  juice 
after  death.  His  observations  on  this  subject 
confirm  the  foregoing  view  of  digestion,  for  he 
found  part  of  the  stomach  digested  when  the 
food  it  contained  remained  undigested,  in  the  case 
of  a man  killed  immediately  after  a full  meal. 
This  I have  often  observed  in  rabbits,  when  the 
animal  has  been  killed  immediately  after  eating, 
and  allowed  to  lie  undisturbed  for  some  time. 
On  opening  the  abdomen  we  have  found  the 
great  end  of  the  stomach  soft,  eaten  through, 
sometimes  wholly  consumed,  the  food  being  only 
covered  by  the  peritoneum,  or  lying  quite  bare 
for  the  space  of  an  inch  and  a half  in  diameter, 
£tnd  part  of  the  contiguous  intestines,  in  the  last 
case,  also  consumed ; while  the  cabbage,  which 
the  animal  had  taken,  lay  in  the  centre  of  the 
stomach  unchanged,  if  we  except  the  alteration 
which  had  taken  place  in  the  external  parts  of 
the  mass  it  had  formed,  in  consequence  of  im- 
bibing gastric  juice  from  the  half  digested  food 
in  contact  with  it.  We  sometimes  found  the 
great  end  of  the  stomach  digested  within  an  hour 
and  a half  after  death ; it  was  more  frequently 
found  so  when  the  animal  had  lain  dead  for 
many  hours,  The  great  end  of  the  stomach  is 


160 


not  always  dissolved,  however  long  the  animal 
has  lain  dead.  This  seems  only  to  take  place 
when  there  happens  to  be  a greater  supply  than 
usual  of  gastric  juice.  Thus  we  always  observed 
it  most  apt  to  happen  when  the  animal  had  eaten 
voraciously.  Why  it  should  happen  without  the 
food  being  digested  is  evident,  from  what  has 
been  said.  Soon  after  death,  the  motion  of  the 
stomach,  which  is  constantly  carrying  on  towards 
the  pylorus  the  most  digested  food,  ceases.  Thus 
the  food,  which  lies  next  the  surface  of  the  sto- 
mach, being  fully  saturated  with  gastric  juice, 
neutralises  no  more;  and  no  new  food  being  pre- 
sented to  it,  it  necessarily  acts  on  the  stomach 
itself,  now  deprived  of  life,  and  on  this  account, 
as  Mr.  Hunter  justly  observes,  equally  subject 
to  its  action  with  other  dead  animal  matter.-  It 
is  remarkable  that  the  gastric  juice  of  the  rabbit, 
which  in  its  natural  state  refuses  animal  food, 
should  so  completely  digest  its  own  stomach,  as 
not  to  leave  a trace  of  the  parts  acted  on.  I 
never  saw  the  stomach  eaten  through  except  in 
the  large  end.  In  other  parts  its  internal  mem 
brane  is  sometimes  injured. 

Keeping  in  view  the  foregoing  account  of  the 
process  of  digestion  in  the  rabbit,  it  will  be  inte- 
resting to  trace  the  effect  produced  on  it  by  de- 
priving the  stomach  of  a great  part  of  its  uervous 
influence,  which  is  done  by  dividing  the  eighth 
pair  of  nerves 


161 


The  division  of  the  eighth  pair  of  nerves, 
which  I have  had  such  frequent  occasion  to 
mention,  is  one  of  the  oldest  physiological  ex- 
periments of  which  we  have  any  account.  It 
was  performed  by  several  of  the  ancients,  and 
has  been  repeated  by  a great  many  physiologists 
in  modern  times.  Valsalva  is  among  the  first 
who  gave  any  distinct  account  of  its  effects  on 
the  stomach.  He  observes  that  it  impedes  di- 
gestion, and  even  prevents  the  food  passing  from 
the  oesophagus  into  the  stomach.  The  cause  of 
part  of  the  food  being  found  in  the  oesophagus  I 
have  had  occasion  to  point  out  above.  Haller 
frequently  repeated  this  experiment,  and  ob- 
serves that  the  powers  of  digestion  were  always 
suspended  by  it.  Since  his  time  it  has  often 
been  made  by  others  with  the  same  result.* 

* It  is  said  that  M.  Maguedie  has  divided  the  eighth  pair 
of  nerves  immediately  above  the  diaphragm,  and  found  that 
the  stomach  is  still  capable  of  performing  its  functions.  Of 
the  effects  of  the  division  of  the  eighth  pair  of  nerves  at  this 
place  I cannot  speak,  as  I have  never  seen  the  experiment 
made.  Its  effects  on  the  stomach,  it  is  evident,  may  be  dif- 
ferent from  that  of  the  division  of  these  nerves  in  the  neck, 
because  they  form  various  connections  with  the  great  sym- 
pathetic nerve  in  the  thorax.  By  dividing  the  eighth  pair 
of  nerves  in  the  neck,  the  stomach  is  deprived  of  the  whole, 
or  nearly  the  whole,  power  of  these  nerves.  It  seems  sur- 
prising that  a warm-blooded  animal  should  live  long  enough 
to  afford  proof  of  the  functions  of  the  stomach  being  per- 
fectly performed,  after  so  severe  and  tedious  an  operation, 
in  the  cavity  of  the  thorax. 

23 


162 


I was  greatly  puzzled  at  first  by  observing, 
that  if  the  animal  be  allowed  to  live  for  a consi- 
derable time  after  the  division  of  these  nerves, 
the  food  remaining  in  the  stomach  is  always 
found  undigested,  and  nearly  in  the  same  state 
in  all  parts  of  the  stomach.  This  effect  was 
uniform;  I never  saw  it  otherwise.  Yet  we  must 
conceive  that  at  the  time  the  animal  last  eats, 
there  is  some  food  more  or  less  digested  in  its 
stomach,  and  some  gastric  juice  to  act  on  part 
of  that  just  received  into  it.  The  foregoing 
statements  explain  the  difficulty.  The  division 
of  the  eighth  pair  of  nerves  destroys  the  secre- 
tion of  the  gastric  juice,  but  tlie  animal  still 
living,  and  the  motions  of  the  alimentary  canal 
being  independent  of  the  nervous  influence,*  the 
usual  motions  of  the  stomach  continue,  and  send 
onwards  into  the  intestines  all  the  food  which  is 
digested,  and  consequently  can  apply  to  the  sto- 
mach that  stimulus  which  excites  its  natural 
motions.  Thus  it  is  evident  from  the  foregoing 
observations,  that  the  undigested  food  must  at 
length  come  into  contact  with  it.  As  soon  as 
this  happens,  the  usual  secretions  not  being  sup- 
plied to  produce  the  proper  change  in  it,  au 
unnatural  motion  is  excited;  hence  the  efforts  to 
vomit,  which  always  ensue  in  about  au  hour,  au 
hour  and  a half,  or  two  hours  after  the  division 


See  Chap.  VI. 


163 


of  the  nerves,  marking;  the  time  when  the  sto- 
mach, having  sent  towards  the  pylorus  its  di- 
gested contents,  begins  to  feel  the  effects  of 
undigested  food  coming  into  contact  with  it.  If 
the  animal  be  allowed  to  eat  after  the  opera- 
tion, the  vomiting  almost  immediately  ensues ; 
the  food,  as  appears  from  the  above  statement, 
and,  indeed,  as  is  evident  from  the  way  in  which 
it  enters  the  stomach,  almost  immediately  coming 
in  contact  with  some  part  of  the  small  curvature, 
and  there  not  meeting  with  the  secretions,  which, 
as  explained  above,  make  the  first  impression  on 
it.  Thus  we  see  the  cause  of  the  efforts  to  vomit, 
which  ensue  on  the  division  of  the  eighth  pair  of 
nerves ; and  why,  if  the  animal  be  allowed  to  live 
for  a certain  time  after  the  operation,  nothing  but 
undigested  food  is  found  in  the  stomach. 

SECT.  II. 

On  the  effects  on  the  stomach  and  lungs  of  de- 
stroying certain  'portions  of  the  spinal  marrow , 
compared  with  those  of  dividing  one  or  both  of 
the  eighth  pair  of  nerves. 

From  the  extreme  irregularity  of  the  motions 
of  the  alimentary  canal,  I have  already  had  occa- 
sion to  observe,  we  cannot  ascertain  whether  it  is 
subject  to  the  influence  of  the  different  parts  of 


the  brain  and  spinal  marrow  in  the  way  in  which 
this  has  be.en  done  respecting  the  heart.  I there- 
fore endeavoured  to  ascertain  this  point  by  with- 
drawing from  the  most  important  part  of  this  canal, 
the  stomach,  the  influence  of  different  parts  of  these 
organs,  and  observing  the  effects  produced  on  it. 

As  we  have  seen  the  office  of  the  stomach  de- 
stroyed by  the  division  of  the  eighth  pair  of 
nerves,  we  should  at  first  view  infer,  that  it  is 
from  the  brain  alone  that  the  stomach  derives  its 
nervous  influence.  But  although  the  process  of 
digestion  is  suspended  by  the  division  of  these 
nerves,  it  does  not  follow  that  the  stomach  may 
not  derive  nervous  influence  from  other  sources, 
because  the  loss  of  any  considerable  part  of  its 
nervous  energy  may  destroy  its  function.  Be- 
sides, its  remaining  sensibility,  indicated  by  the 
efforts  to  vomit,  proves  that  its  nervous  influence 
is  not  wholly  withdrawn  by  dividing  the  eighth 
pair  of  nerves. 

If,  then,  the  nervous  influence  be  not  supplied  to 
the  stomach  by  the  eighth  pair  of  nerves  alone, 
but  also,  as  we  have  reason  to  believe  from  the 
evidence  of  anatomy,  by  nerves  arising  from  dif- 
ferent parts  of  the  spinal  marrow,  it  is  evident,  that 
cutting  off  its  supply  from  any  considerable  part 
of  this  organ,  while  Ave  leave  the  eighth  pair  en- 
tire, must  affect  its  power,  though  probably  not 
so  much,  because  the  brain,  Ave  have  reason  to 
believe,  constitutes  the  largest  and  most  impor- 


165 


tant  part  of  the  nervous  system.  To  ascertain 
this  point  the  following  experiments  were  made. 

Exp.  58.  A hole  was  made  about  the  middle 
of  the  spine,  and  the  lower  part  of  the  spinal  mar- 
row destroyed  by  a small  wire.  The  only  ap- 
parent effect  of  the  operation  was  the  total  paraly- 
sis of  the  lower  part  of  the  animal.  It  seemed  to 
be  otherwise  in  health.  It  was  allowed  to  eat 
nothing  for  twelve  or  fourteen  hours.  At  the  end 
of  this  time  it  ate  parsley  very  readily,  and  in 
large  quantity,  without  any  tendency  to  vomit. 
It  lived  twenty-four  hours  after  the  operation,  and 
ate  parsley  from  time  to  time. 

On  opening  the  abdomen  after  death,  the  sto- 
mach was  found  distended  to  a great  degree,  ap- 
parently containing  the  whole  of  the  parsley 
which  had  been  eaten  after  the  operation,  in  an 
undigested  state.  It  had  passed  no  urine  after 
the  operation,  and  the  bladder  was  so  much  dis- 
tended, that  it  rose  above  the  umbilicus.  Some 
faeces  had  passed.  The  lungs  collapsed  on  open- 
ing the  thorax,  but  were  slightly  congested. 

Exp.  59.  In  a full-grown  rabbit  a small  wire 
was  introduced  into  the  spine  at  the  fourth  lum- 
bar vertebra,  by  which  we  endeavoured  to  de- 
stroy the  spinal  marrow  as  far  as  the  first  dorsal 
vertebra.  The  hind  legs  were  rendered  insensi- 
ble and  motionless.  Respiration  was  a little  dis- 
ordered. In  a short  time  after  the  operation  the 
animal  appeared  lively  and  ate  some  parsley. 


166 


The  respiration  continued  to  be  slightly  affected. 
Some  hours  after  the  operation  Mr.  Hastings 
watched  the  animal,  observed  it  to  be  very  cold, 
and  it  shivered,  although  it  was  kept  in  the  same 
temperature  with  other  rabbits,  who  shewed  no 
signs  of  being  cold.  The  rabbit  used  in  the  last 
experiment  also  seemed  cold,  but  not  in  the  same 
degree.  The  respiration  now  seemed  much  dis- 
ordered, and  the  animal  refused  parsley.  It  was 
then  brought  near  a fire  and  wrapped  up  in  flan- 
nel. By  these  means  it  was  soon  relieved,  the 
shivering  ceased,  its  eyes  looked  more  lively,  and 
the  breathing  became  more  free.  It  was  kept 
near  the  fire  as  long  as  it  lived,  and  frequently 
ate  parsley.  It  died  in  twenty-seven  hours  after 
the  operation. 

The  abdomen  was  found  full  of  urine,  the 
bladder  having  been  ruptured.  The  peritonaeum 
was  inflamed,  and  the  rectum  much  distended 
with  faeces.  The  stomach  was  not  much  dis- 
tended. The  parsley  near  the  cardiac  orifice 
was  not  at  all  changed,  and  that  near  the  pyloric 
orifice  very  slightly.  The  membrane  of  the  tra- 
chea and  broi\chia  was  more  vascular  than  natu- 
ral. The  bronchial  cells  were  slightly  loaded 
with  frothy  and  bloody  mucus,  and  there  were 
the  same  red  patches  in  the  lungs  as  after  divid- 
ing the  eighth  pair  of  nerves. 

On  examining  the  spinal  marrow  as  far  as  the 
wire  had  passed  we  found  blood  extravasated  in 


167 


different  parts,  and  its  membranes  were  much  in- 
flamed. Immediately  above  the  opening  the  spi- 
nal marrow  was  quite  destroyed  for  about  an  inch 
in  length.  In  other  places  it  did  not  appear  much 
injured. 

Exp.  60.  I wished  to  ascertain  the  effect  of 
destroying  a smaller  portion  of  the  spinal  marrow 
than  that  destroyed  in  either  of  the  last  experi- 
ments, and  requested  Mr.  Hastings  to  perform 
the  following  experiment,  noting  the  temperature 
of  the  animal  at  the  different  periods  of  it.  In 
a rabbit  about  two  months  old,  fed  on  parsley, 
a small  wire  was  introduced  into  the  spinal  canal, 
at  the  first  lumbar  vertebra,  and  that  part  of  the 
spinal  marrow  which  lies  below  this  vertebra,  de- 
stroyed. After  mentioning  the  other  circumstan- 
ces of  the  experiment,  I shall  throw  together  the 
observations  made  on  the  temperature.  The  ani- 
mal lost  the  power  of  the  lower  extremities,  but 
seemed  in  no  other  way  immediately  affected  by 
the  destruction  of  this  part  of  the  spinal  marrow. 
It  lived  thirty-five  hours. 

On  examining  it  after  death,  the  stomach  was 
found  no  larger  than  natural,  the  parsley  retained 
its  colour,  smell  and  fibrous  texture,  although 
such  a change  had  taken  place  in  it,  as  demon- 
strated a very  slight  degree  of  the  digestive  pro- 
cess. The  duodenum  for  about  an  inch  below 
the  pylorus  was  filled  with  parsley  in  the  same 


168 


state.  The  bladder  and  rectum  were  distended, 
but  not  so  much  as  in  the  two  last  experiments. 
The  lungs  were  slightly  congested. 

It  is  difficult  to  destroy  a large  portion  of  the 
spinal  marrow  without  immediately  killing  the 
animal.  It  must  be  done  very  slowly,  and  even 
with  this  precaution  the  attempt  will  not  always 
succeed.  On  examining  the  lumbar  portion  of  the 
spinal  marrow,  after  death,  it  was  found  com- 
pletely destroyed. 

The  following  are  the  observations  on  the  tem- 
perature. 

The  bulb  of  Farenheit’s  thermometer  intro- 
duced into  the  mouth,  and  kept  there  for  two  mi- 
nutes previous  to  the  experiment,  stood  at  98°. 

The  animal  was  kept  in  a warmer  temperature 
after,  than  before  the  destruction  of  the  lumbar 
portion  of  the  spinal  marrow.  The  temperature 
was  always  measured  by  putting  the  bulb  of  the 
thermometer  into  the  mouth,  and  keeping  it  there 
for  two  minutes. 

Immediately  after  the  operation,  therm.  98c 
In  twelve  minutes  after  it  92° 

In  half  an  hour  after  it  92° 

In  two  hours  and  a half  after  it  - - 98° 

In  five  hours  and  three-quarters  after  it  - 98° 

In  seven  hours  and  a quarter  after  it  - 98° 

In  nine  hours  after  it  - - - - 96° 

In  ten  hours  after  it  - - - - 95° 


169 

The  animal  during  all  this  time  appeared  live- 
ly and  eat  parsley. 

In  eleven  hours  after  it,  therm.  - - 96° 

In  twelve  hours  after  it  - - - - 97° 

Night  coming  on,  the  temperature  was  not  mea- 
sured again  for  thirteen  hours.  In  the  morning 
the  rabbit  appeared  lively  and  eat  readily. 

In  twenty-five  hours  after  the  operation, 


therm.  - 

88° 

In  twenty-seven  hours  after  it,  therm. 

- 81° 

In  twenty-nine  hours  after  it 

88° 

In  thirty  hours  after  it  - 

- 81° 

In  thirty-one  hours  after  it  - 

84® 

In  thirty-three  hours  after  it  - 

- 80° 

The  animal  still  continued  to  eat.  In  thirty- 
four  hours  after  the  operation  the  temperature 
was  75°.  In  an  hour  after  this,  the  animal  died. 
This  animal  did  not  appear  nearly  so  cold  as  that 
in  the  preceding  experiment,  in  which  a larger 
and  more  important  part  of  the  spinal  marrow 
was  destroyed. 

Thus  we  find  the  function  of  the  stomach  im- 
peded by  depriving  it  of  the  influence  of  any  con- 
siderable part  of  the  spinal  marrow,  and  it  seems 
only  more  affected  by  the  division  of  the  eighth 
pair  of  nerves,  in  proportion  to  the  greater  extent 
and  importance  of  the  brain. 

It  is  remarkable,  that  the  result  of  the  first  of 
these  experiments  is  the  same  with  that  which  M„. 
le  Grallois  obtained  when  he  had  divided  one  of 


170 


the  eighth  pair  of  nerves  in  a Guinea  pig.  The 
animal  did  not  vomit,  and  the  stomach  was  found 
distended  to  a great  size,  apparently  containing 
all  the  food  it  had  taken  after  the  operation,  in  an 
undigested  state.  This  coincidence  demonstrates 
how  much  the  same  the  effect  on  the  stomach  is, 
whether  we  deprive  it  of  part  of  the  nervous  in- 
fluence, which  it  receives  from  the  brain,  or  part 
of  that  which.it  receives  from  the  spinal  marrow. 
Mr.  Hastings,  at  my  request,  made  this  experi- 
ment on  a rabbit. 

Exp.  61.  One  of  the  eighth  pair  of  nerves  was 
divided  in  a rabbit.  No  difficulty  of  breathing 
immediately  ensued.  The  rabbit  continued  to 
eat  from  time  to  time,  with  occasional  attempts  to 
vomit,  and  once  it  brought  up  a little  of  the  pars- 
ley. It  laboured  under  a slight  degree  of  dysp- 
noea. A short  time  before  its  death,  which  hap- 
pened in  twenty-four  hours  and  a half  after  the 
division  of  the  nerves,  the  dyspnoea  suddenly  in- 
creased with  restlessness. 

On  examining  the  stomach  after  death,  we  did 
not  find  it  much  distended.  The  food  was  very 
little  changed.  The  oesophagus  did  not  contain 
much  food  in  the  upper,  in  the  lower  part  it  was 
much  distended  with  it.  The  bronchia  were 
much  less  loaded  than  when  both  nerves  had 
been  divided.  The  larynx  was  found  quite  full 
of  the  parsley,  in  consequence  of  the  epiglottis's 
having,  by  some  strange  accident,  been  caught  in 


171 


the  membrane  of  the  pharynx,  so  as  to  prevent 
its  falling  down  on  the  glottis.  In  consequence 
of  this  accident,  which  was  evidently  the  cause 
of  death,  the  experiment  was  repeated. 

Exp.  62.  One  of  the  eighth  pair  of  nerves  was 
divided  in  a rabbit.  It  eat  soon  after  the  opera- 
tion, but  did  not  vomit  till  two  hours  and  a half 
after  it,  and  then  dyspnoea  came  on.  The  breath- 
ing at  times  was  almost  free,  and  the  vomiting 
only  occurred  at  intervals.  Both  subsided  when 
it  was  prevented  eating.  It  died  forty-five  hours 
after  the  operation. 

The  stomach  was  found  after  death  larger  than 
natural,  being  distended  with  flatus,  and  con- 
taining more  food  than  usual.  For  the  most  part 
the  parsley  was  in  the  same  state  as  when  taken 
into  the  stomach,  both  in  appearance  and  smell. 
In  some  places  it  was  slightly  changed.  There 
was  undigested  parsley  in  the  duodenum,  to  the 
distance  of  about  an  inch  from  the  stomach.  The 
lower  end  of  the  oesophagus  contained  a little  pars- 
ley. There  was  none  in  any  other  part  of  it. 

When  we  compare  this  experiment  with  the 
experiments  in  which  galvanism  was  used,  the 
difference  of  result  is  very  striking.  Here,  al- 
though only  one  nerve  was  divided,  parsley  had 
remained  in  the  stomach  and  duodenum  unchang- 
ed for  nearly  two  days.  There,  although  both 
nerves  were  divided,  the  whole  food  contained  in 
the  stomach,  although  it  had  lain  in  it  a compara- 


tively  short  time,  was  found  nearly  as  much 
changed  as  in  the  stomach  of  a healthy  rabbit. 

The  membrane  of  the  trachea  was  of  a darker 
colour  than  natural,  its  vessels  being  distend- 
ed with  blood,  and  there  was  some  frothy  mucus 
in  it.  The  lungs  were  slightly  congested.  The 
membrane  of  the  bronchia  was  too  vascular,  and 
the  air-cells  contained  some  frothy  mucus.  All 
these  appearances  existed  in  a much  less  degree 
than  when  both  nerves  were  divided.  The  lungs 
collapsed  imperfectly  on  opening  the  chest. — 
There  were  some  dark  coloured  spots  on  them. 

If  the  reader  will  take  the  trouble  to  compare 
these  appearances  with  those  observed  when  part 
of  the  spinal  marrow  was  destroyed,  particularly 
in  Experiment  59,  lie  will  see  that  the  division 
of  one  of  the  eighth  pair  of  nerves  produces  near- 
ly the  same  effect  on  the  lungs  and  stomach,  as 
the  destruction  of  part  of  the  spinal  marrow. 

I wished  to  see  the  effect  on  the  stomach  and 
lungs  of  destroying  nearly  the  whole  spinal  mar- 
row. But  with  all  the  precautions  that  could  be 
taken  the  animal  died  almost  immediately.  It  is 
difficult  indeed  to  prevent  immediate  death,  when 
as  much  of  it  is  destroyed  as  in  Experiments  58 
and  59. 

There  is  still  another  point  in  this  part  of  the 
subject,  which  remains  to  be  ascertained.  Do 
the  effects  observed  on  the  stomach  and  lungs, 
when  part  of  the  spinal  marrow  is  destroyed. 


173 

arise  from  tlie  destruction  of  that  part;  that  is, 
from  the  ceasing  of  its  office,  or  from  the  influence 
of  the  brain  on  the  spinal  marrow  being  thus  li- 
mited ? It  is  evident,  that  if  the  former  opinion  be 
correct,  the  division  of  the  spinal  marrow  in  the 
middle,  will  not  produce  the  same  effects  as  the 
destruction  of  the  lower  half.  If  the  other  opi- 
nion be  correct,  these  must  produce  precisely  the 
same  effects. 

Exp.  63.  The  spine  was  divided  in  an  old 
rabbit,  about  the  same  place  at  which  it  was 
opened  in  order  to  destroy  the  lower  half  of  the 
spinal  marrow  in  Experiment  58,  after  which 
there  was  no  motion  in  the  lower  extremities. — 
The  rabbit  seemed  lively  after  the  operation,  and 
continued  to  eat  frequently  till  within  six  hours 
of  its  death.  It  died  in  twenty-seven  hours  and 
a half  after  the  division  of  the  spinal  marrow. — 
It  had  not  vomited,  and  had  had  little  or  no 
dyspnoea. 

On  examining  the  stomach  after  death,  it  was 
not  found  more  distended  than  natural.  The 
food  it  contained,  was  nearly  as  well  digested  as 
in  the  stomach  of  a healthy  rabbit.  The  con- 
tents of  the  duodenum  had  completely  undergone 
the  proper  change.  The  bladder  and  rectum 
were  distended,  but  not  so  much  as  after  the  de- 
struction of  the  lower  part  of  the  spinal  marrow. 

The  lungs  collapsed  on  opening  the  thorax, 
but  contained  a little  frothy  mucus. 


174 


On  examining  the  spine  it  was  found  to  have 
been  completely  divided. 

On  comparing  this  experiment  with  Experi- 
ment 58 , we  see  that  here  the  lower  part  of  the 
spinal  marrow  still  performed  its  office,  and  sup- 
plied its  portion  of  nervous  influence  to  the  gang- 
lia, although  the  communication  between  it  and 
the  brain  was  cut  off.  The  reader  must  have 
perceived  through  the  whole  of  these  experi- 
ments, that  any  considerable  diminution  of  the 
nervous  influence,  almost  wholly  deprives  the  sto- 
mach of  its  power ; and  even  the  slightest  dimi- 
nution of  it  seems  to  be  felt.  I have  no  doubt, 
that  we  may  ascribe  the  very  slight  derange- 
ments observed  in  the  stomach  and  lungs  in  the 
last  experiment,  to  the  destruction  of  function, 
that  must  have  taken  place  in  the  part  of  the  spi- 
nal marrow  at  which  it  was  divided.  The  bruise 
occasioned  by  the  wound  must  of  course  have  de- 
stroyed the  function  of  a small  part  on  each  side. 

Thus  we  find  that  although  we  cannot  by  agents 
applied  to  different  parts  of  the  brain  and  spinal 
marrow,  ascertain  how  far  the  stomach  and  lungs 
are  under  their  influence,  we  may,  by  withdraw- 
ing the  influence  of  different  parts  of  the  former 
organs,  prove  that  the  stomach  and  lungs,  like 
the  heart,  are  capable  of  being  influenced  through 
every  part  of  them. 


175 


CHAP.  VIII. 

On  the  cause  of  Animal  Temperature  . 

We  are  now  to  attend  to  the  temperature  of 
the  animals  in  those  experiments,  in  which  por- 
tions of  the  spinal  marrow  were  destroyed.  It 
appears  from  them  that  while  the  destruction  of 
part  of  the  spinal  marrow  impedes  the  office  of 
secreting  surfaces,  it  also  lessens  the  evolution 
of  caloric.  Mr.  Brodie,  in  the  Croonian  Lecture 
for  1810,  gave  an  account  of  experiments  which 
led  to  the  inference,  that  the  production  of  ani- 
mal temperature  is  under  the  influence  of  the  ner- 
vous system : and  in  the  Philosophical  Transac- 
tions of  1812,  he  relates  additional  experiments, 
tending  to  strengthen  this  inference.  In  the  se- 
cond Section  of  the  last  Chapter,  I have  had  oc  - 
casion to  relate  experiments  made  for  other  pur- 
poses, which  tend  in  a striking  manner  to  confirm 
the  opinion  of  Mr.  Brodie.  He  found  that  poi- 
sons impairing  the  vigour  of  the  nervous  system 
impair  the  temperature.  In  the  foregoing  expe- 
riments lessening  the  extent  of  this  system  by  de- 
stroying part  of  the  spinal  marrow  had  the  same 
effect. 

Towards  the  conclusion  of  the  latter  of  the 
above  papers,  Mr.  Brodie  observes,  “ The  facts 
here,  as  well  as  those  formerly  adduced,  go  far 


176 


towards  proving,  that  the  temperature  of  warm- 
blooded animals  is  considerably  under  the  in- 
fluence of  the  nervous  system ; but  what  is  the 
nature  of  the  connection  between  them?  Whether 
is  the  brain  directly  or  indirectly  necessary  to 
the  production  of  heat  ? These  are  questions  to 
which  no  answers  can  be  given,  except  such  as 
are  purely  hypothetical.  At  present  we  must  be 
content  with  the  knowledge  of  the  insulated  fact : 
future  observations  may  perhaps  enable  us  to 
refer  it  to  some  more  general  principle. ” 

The  various  phenomena  of  animal  tempera- 
ture, and  the  experiments  on  this  subject,  related 
in  the  last  chapter,  compared  with  those  on  se- 
creting surfaces,  seem  to  me  to  prove,  that  the 
caloric,  which  supports  animal  temperature,  is 
evolved  by  the  same  means,  namely,  the  action 
of  the  nervous  influence  on  the  blood,  by  which 
the  formation  of  the  secreted  fluids  is  effected, 
and  consequently  that  it  is  to  be  regarded  as  a 
secretion.  If  this  view  of  the  subject  be  correct, 
and  galvanism  be  capable  of  performing  the 
functions  of  the  nervous  influence,  it  ought  to 
occasion  an  evolution  of  caloric,  as  it  effects  the 
formation  of  secreted  fluids,  from  arterial  blood, 
after  the  nervous  influence  is  withdrawn.  To 
ascertain  this  point,  the  following  experiments 
were  made. 

Exp.  61.  A cup  was  placed  in  water  of  the 
temperature  of  98°  of  Farenheit’s  thermometer, 


1 77 


which  was  ascertained  to  be  the  temperature  of 
the  rabbit,  on  whose  blood  the  experiment  was 
made,  by  placing  the  bulb  of  the  thermometer  in 
the  rabbit’s  mouth,  and  allowing  it  to  remain 
there  for  two  minutes.  The  temperature  of  all 
the  rabbits  used  in  the  following  experiments 
was  ascertained  in  the  same  way.  Blood  was 
received  into  the  cup  from  one  of  the  carotid  ar- 
teries. The  bulb  of  a small  thermometer,  raised 
to  98°,  and  the  wires  from  the  different  ends  of 
the  galvanic  trough,  abovementioned,  the  whole 
trough  being  charged,  were  immersed  into  it. 
The  blood  had  been  in  the  cup  about  two  mi- 
nutes before  the  whole  apparatus  was  arranged. 
The  same  quantity  of  blood,  taken  from  the  same 
vessel  of  another  rabbit  of  the  same  age  and  tem- 
perature, was  received  into  a cup,  also  placed  in 
water  of  the  temperature  of  98°.  So  far,  how- 
ever, from  perceiving  any  evolution  of  caloric 
from  the  effects  of  the  galvanism,  the  blood  in 
the  galvanised  cup  seemed  to  cool  rather  faster 
than  that  in  the  other.  The  appearance  of  the 
blood  in  the  two  cups,  however,  was  very  dif- 
ferent : that,  in  which  the  wires  were  immersed, 
assumed  a dark  venous  colour,  and  most  of  the 
coagulum,  which  had  appeared  to  form  more  ra- 
pidly in  this  than  the  other  blood,  was  soon  dis- 
solved, the  blood  again  becoming  liquid.  The 
blood  in  the  other  cup  retained  the  florid  colour, 
and  coagulated  as  usual. 

25 


178 


It  occurred  to  me,  that  the  galvanism  in  this 
experiment  had  perhaps  been  applied  too  late  to 
produce  all  its  effect  on  the  blood.  For  we  must 
suppose  the  changes  of  this  fluid  to  commence  as 
soon  as  it  leaves  the  vessels  : with  the  assistance 
of  Mr.  Hastings,  and  another  gentleman,  there- 
fore, I repeated  the  experiment  in  the  following 
manner. 

Exp.  65.  The  rabbits  were  chosen  of  the  same 
size  and  temperature,  the  thermometer  in  the 
mouth  of  each  standing  at  98°.  The  cups  were 
disposed  as  in  the  last  experiment ; the  water,  in 
which  they  stood,  being  at  the  temperature  of 
98°.  Into  the  one  cup  nothing  was  put  but  the 
thermometer ; into  the  other,  the  thermometer 
and  the  two  wires  from  the  different  ends  of  the 
galvanic  trough,  one  on  each  side  of  the  bulb ; 
the  thermometer,  raised  to  98°,  being  put  into 
the  cups  at  the  moment  the  blood  began  to  flow. 
Assistants  held  the  rabbits  while  Mr.  Hastings 
divided  the  carotid  arteries  previously  exposed. 
I observed  the  thermometer,  and  a person  hav- 
ing a watch  marking  seconds,  noted  down  the 
changes  of  the  thermometer  as  I mentioned  them, 
and  the  times  at  which  they  took  place.  The 
experiment  Avas  made  first  on  the  blood  of  the 
one  rabbit,  and  then  on  that  of  the  other;  but 
to  save  repetition,  I relate  it  as  if  it  had  been 
made  on  both  at  the  same  time.  The  tempe- 
rature of  the  mouth  is  always  the  temperature 


179 


of  the  blood  on  its  first  flowing  from  the  ves- 
sel. In  the  cup,  where  there  was  only  the  ther- 
mometer, one  minute  after  the  blood  began  to  flow 
into  it,  the  thermometer  stood  at  97°?  in  a quarter 
of  a minute  more  it  stood  at  96°,  and  so  on  gra- 
dually falling ; for  it  is  to  be  observed,  that  al- 
though the  cups  stood  in  water  of  98°,  the  air  in 
them  was  more  than  ten  degrees  lower. 

In  the  cup,  where  the  wires  were,  one  minute 
after  the  blood  had  begun  to  flow  into  it,  the  ther- 
mometer stood  at  100°,  in  half  a minute  more  at 
102°,  in  half  a minute  more  at  100°,  in  a minute 
more  at  99°,  in  half  a minute  more  at  98°,  that  is 
in  three  minutes  and  a half  after  the  blood  had 
begun  to  flow  into  the  cup.  After  this,  the  ther- 
mometer gradually  fell. 

While  the  above  changes  of  temperature  went 
on,  the  blood  in  the  galvanised  cup  began  to 
assume  a dark  colour  about  the  positive  wire. 
But  it  appears  from  the  preceding  experiment, 
that  the  evolution  of  caloric  was  not  connected 
with  this  change  of  colour,  which  took  place  as 
quickly  where  no  caloric  was  disengaged.  Be- 
sides the  caloric  ceased  to  be  evolved  soon  after 
the  dark  colour  appeared  about  this  wire,  and  by 
keeping  up  the  supply  of  galvanism,  the  dark  co- 
lour continued  to  extend  after  the  evolution  of 
caloric  had  ceased,  till  the  whole  blood  in  the 
cup  assumed  this  colour.  Air  bubbles  arose 
around  both  wires.  Around  the  negative  wire 


180 


they  continued  to  rise  in  such  quantity  as  to  form 
a considerable  accumulation  of  froth.  All  these 
appearances  took  place  equally,  whether  the  wires 
were  immersed  in  the  blood  at  the  moment  it 
flowed  from  the  vessel,  or  after  the  time  had 
elapsed,  at  which  they  occasioned  an  evolution 
of  caloric. 

Exp.  66.  That  I might  be  assured  that  we 
were  not  deceived  in  the  first  experiment,  we  al- 
lowed blood  to  flow  from  the  carotid  artery  of  a 
rabbit  into  a cup  placed  as  above,  and  after  it  had 
remained  in  the  cup  only  about  a minute  and  a 
half,  during  which  no  change  of  appearance  took 
place  in  it,  the  wires  and  thermometer  were  im- 
mersed into  it.  The  change  of  colour,  and  other 
phenomena  mentioned  above,  took  place  exactly 
as  before  ; but  there  was  no  evolution  of  caloric, 
the  blood  continued  gradually  to  cool. 

Exp.  67.  In  a rabbit,  whose  temperature  was 
only  96°,  both  carotids  were  exposed.  It  was 
then  held  over  a cup  placed  in  water  of  the  same 
temperature,  and  containing  the  galvanic  wires. 
Both  arteries  were  divided,  and  the  blood  allowed 
to  flow  into  the  cup  ; a thermometer,  raised  to 
96°,  being  at  the  same  moment  placed  in  the  cup 
between  the  wires.  In  a quarter  of  a minute  af- 
ter the  blood  began  to  flow,  the  thermometer  rose 
to  98°,  in  half  a minute  afterwards  to  99°.  In  a 
quarter  of  a minute  more  it  had  fallen  to  98°,  in  a 
quarter  of  a minute  it  was  still  98°,  in  half  a mi- 


181 


nute  more  97°j  in  a quarter  of  a minute  more,  that 
is,  two  minutes  after  the  blood  began  to  flow,  it 
returned  to  96°,  after  this  it  continued  gradually 
to  fall.  The  low  temperature  of  this  animal,  and 
the  evolution  of  caloric,  being  less  than  in  Expe- 
riment 65,  probably  arose  from  the  same  cause. 

I wished  to  ascertain,  whether  galvanism  oc- 
casions a similar  evolution  of  caloric  from  venous 
blood. 

Exp.  68.  Blood  was  taken  from  the  arm  of  a 
person,  whose  temperature,  as  appeared  by  put- 
ting the  bulb  of  a thermometer  into  the  mouth, 
was  98°.  The  blood  was  received  into  a cup 
placed  in  water  of  the  same  temperature,  into 
which  were  put  the  wires  from  the  galvanic  trough. 

The  thermometer,  raised  to  98°,  was  put  into  the 
cup  as  soon  as  the  blood  began  to  flow  into  it. 

It  continued  gradually  to  sink,  at  no  moment  giv- 
ing the  least  indication  of  the  evolution  of  caloric.  > 
This  experiment  was  repeated  in  the  same  way, 
and  with  the  same  result. 

I wished  to  try  the  effect  of  galvanism  on  blood 
returning  from  the  viscera. 

Exp.  69.  For  this  purpose  the  vena  cava  of  a 
young  rabbit,  whose  temperature  was  rather 
above  100°,  was  opened,  and  the  blood  from  it  al- 
lowed to  flow  into  a cup,  placed  in  water  of  rather 
a higher  temperature  than  100°  ; the  thermome- 
ter, raised  to  the  same  temperature,  and  the  gal- 
vanic wires  being  placed  in  a cup,  while  the  blood 


182 


was  flowing.  No  evolution  of  caloric  whatever 
took  place.  As  the  greater  part  of  the  bulb  of 
the  thermometer  in  this  experiment  remained  un- 
covered, the  quantity  of  blood  obtaiued  from  this 
rabbit  being  small,  the  experiment  was  repeated 
on  a cat. 

Exp.  70.  The  temperature  of  the  cat  was  97-° 
This  experiment  was  conducted  in  exactly  the 
same  way  as  the  last,  except  that  the  tempera- 
ture of  the  water  was  9/°>  and  the  thermometer, 
at  the  time  of  its  introduction  into  the  cup,  raised 
to  the  same  degree.  The  blood  flowed  freely  into 
the  cup.  The  thermometer  indicated  no  evolu- 
tion of  caloric.  The  galvanism  produced  the 
same  visible  effects  on  the  venous  as  it  had  done 
on  the  arterial  blood,  except  that  the  colour  of 
the  former  remained  unchanged. 

Experiments  65  and  67  prove,  that  by  the 
power  of  galvanism,  caloric  is  evolved  from  ar- 
terial blood.  When  this  circumstance  is  com- 
pared with  the  experiments  proving  the  power 
of  galvanism  in  effecting  the  formation  of  the 
secreted  fluids,  and  with  the  fact,  that  the  tem- 
perature of  animals  is  lessened  by  impairing  the 
vigour,  or  destroying  part  of  the  nervous  system, 
it  will  be  admitted  to  afford  a strong  argument  in 
favour  of  the  identity  of  the  nervous  influence 
and  galvanism.  I need  hardly  observe,  that  no 
caloric  being  evolved  by  the  power  of  galvanism 
from  venous  blood,  that  is,  blood  which  has  al- 


183 

ready  undergone  the  secreting  power,  is  an  ad- 
ditional argument  in  favour  of  this  opinion. 

In  the  seventh  volume  of  the  Medico- Chirur- 
gical  Transactions,  Mr.  Henry  Earle  notices 
many  cases  of  palsy,  in  which  the  temperature 
of  the  paralytic  limb,  although  the  pulse  was 
good,  was  lower  than  that  of  the  rest  of  the 
body.  In  the  first  case  which  he  mentions,  he 
found,  that  passing  the  electric  fluid  through  the 
limb,  raised  its  temperature.  I am  sorry  that  I 
have  not  had  an  opportunity  of  repeating  this 
experiment,  either  with  electricity  or  galvanism, 
having  not  met  with  any  case  of  palsy,  since  I 
read  Mr.  Earle’s  paper,  in  which  the  tempera- 
ture was  lessened. 

Exjj.  71*  Hy  the  foregoing  experiments  the 
idea  is  suggested  that  some  gaseous  fluid  pro- 
bably escapes  from  arterial  blood,  soon  after  it 
leaves  the  vessel.  To  ascertain  whether  this  is 
the  case,  a glass  of  such  a shape  that  the  small- 
est globule  of  air  could  be  seen  in  it,  was  filled 
with  and  inverted  over  mercury.  A considera- 
ble part  of  the  femoral  artery  of  a large  rabbit, 
whose  sensibility  had  been  nearly  destroyed  by 
opium,  was  then  exposed  and  divided  under  the 
glass.  The  blood  immediately  rose  into  the 
glass,  and  was  allowed  to  remain  undisturbed 
for  a quarter  of  an  hour,  but  no  gaseous  fluid 
was  disengaged  from  it.  In  performing  this  ex- 
periment, if  great  care  be  not  taken,  the  hair  of 


184 


the  animal  and  hands  of  the  assistants  may  con- 
vey a little  air  under  the  glass,  by  which  we 
were  repeatedly  foiled  in  making  the  experiment. 
The  artery  must  not  be  held  deep  in  the  mercury, 
else  the  weight  of  the  metal,  by  compressing  it, 
will  prevent  the  escape  of  the  blood. 

The  glass  into  which  the  blood  was  received, 
rose  only  about  an  inch  and  a half  above  the  sur- 
face of  the  mercury.  Had  it  risen  high  enough 
to  take  off  any  considerable  part  of  the  pressure 
of  the  atmosphere,  the  experiment,  it  is  evident, 
would  not  have  been  a fair  one.  What  elastic 
fluids  may  be  disengaged  from  arterial  blood, 
when  that  pressure  is  removed  from  it,  is  a dif- 
ferent question.  It  appears  from  this  experiment, 
that  the  difference  of  the  effect  of  galvanism  on 
this  blood  at  the  moment  it  leaves  the  vessel,  and 
two  minutes  after  it  has  left  it,  does  not  arise 
from  the  escape  of  any  gaseous  fluid. 

When  speaking  of  the  order  in  which  the 
functions  of  the  animal  body  cease  in  dying,  I 
shall  have  occasion  to  relate  some  additional 
experiments  on  animal  temperature. 


185 


CHAP.  IX. 

On  the  use  of  the  Ganglions . 

It  appears  from  experiments  related  in  the  first 
and  second  chapters  of  the  present  part  of  this 
treatise,  that  the  motion  of  the  heart,  though  in- 
dependent of,  may  be  influenced  through,  every 
part  of  the  brain  and  spinal  marrow.  It  seems 
also  ascertained,  by  experiments  related  in  the 
same  chapters,  that  the  blood  vessels  hear  the 
same  relation  to  the  nervous  system  with  the 
heart.  Their  power  is  equally  independent  of 
this  system,  and  they  are  influenced  in  the  same 
way  by  agents  acting  through  it.  We  cannot, 
we  have  seen,  affect  the  muscles  of  voluntary 
motion  in  the  extremities,  by  agents  applied  to 
the  upper  parts  of  the  brain,  yet  the  vessels  of 
their  most  extreme  parts  obey  agents  applied 
even  to  the  upper  surface  of  this  organ. 

It  appears  from  experiments  related  in  Chap- 
ter VI,  that  the  muscular  power  of  the  alimen- 
tary canal  is  also  independent  of  the  nervous 
system.  It  is  impossible,  for  reasons  which 
have  been  laid  before  the  reader,  to  ascertain, 
by  experiments  similar  to  those  relating  to  the 
heart  and  blood  vessels,  whether  the  alimentary 
canal  also  is  subject  to  the  influence  of  every 

part  of  the  brain  and  spinal  marrow.  With  re- 

26 


186 


spect  to  it,  therefore,  I attempted,  in  the  second 
Section  of  Chapter  VII,  to  determine  this  point 
in  a different  way.  Although  the  muscular  power 
of  the  alimentary  canal  is  independent  of  the 
brain  and  spinal  marrow,  its  secreting  power,  we 
have  found,  is  wholly  dependent  on  them;  I en- 
deavoured, therefore,  to  ascertain  whether  it  is 
subject  to  every  part  of  these  organs,  by  with- 
drawing the  influence  of  different  parts  of  them 
from  the  most  important  part  of  it,  the  stomach ; 
and  we  have  seen,  that  when  this  organ  is  de- 
prived of  the  influence  of  any  considerable  part 
either  of  the  brain  or  spinal  marrow,  its  secret- 
ing function  is  deranged,  the  derangement  being 
proportioned  to  the  importance  and  extent  of  the 
part  whose  influence  has  been  withdrawn.  The 
stomach,  therefore,  like  the  heart,  is  capable  of 
being  influenced  by  every  part  of  the  brain  and 
spinal  marrow. 

Here  the  question  arises,  by  what  means  is 
the  one  set  of  organs  subjected  to  the  influence 
of  every  part  of  the  other.  We  cannot  suppose 
that  the  former  receive  nerves  from  every  part  of 
the  brain  and  spinal  marrow.  We  know,  indeed, 
that  no  organ  does  so.  The  following  seems  to 
be  the  state  of  the  question.  AVe  see  some  parts 
influenced  by  every  part  of  the  brain  and  spinal 
marrow ; others,  only  by  small  parts  of  them. 
In  the  latter  instances,  we  see  directly  proceeding 
from  those  small  parts,  the  nerves  of  the  parts 


187 


influenced.  In  the  former  instances,  namely, 
where  it  is  found  that  the  part  is  influenced  by 
all  parts  of  the  brain  and  spinal  marrow,  we  do 
not,  in  any  case,  see  nerves  going  directly  from  all 
parts  of  these  organs  to  the  part  influenced,  but 
we  always  see  this  part  receiving  nerves  from  a 
chain  of  ganglions,  to  which  nerves  from  all  parts 
of  the  brain  and  spinal  marrow  are  sent.  It  is, 
therefore,  evident  from  direct  experiments,  that 
the  nerves  issuing  from  ganglions  convey  to  the 
parts,  to  which  they  send  nerves,  the  influence  of 
all  the  nerves  which  terminate  in  these  bodies. 

Such  then  is  the  relation  which  the  most  im- 
portant organs  of  involuntary  motion  bear  to  the 
brain  and  spinal  marrow.  Their  powers  are  in- 
dependent of  both,  yet  they  are  subjected  to  the 
influence  of  every  part  of  both,  communicated 
through  the  medium  of  the  ganglions ; and  when 
we  see  the  other  organs  of  involuntary  motion 
equally  independent  of  the  brain  and  spinal 
marrow,  and  supplied  with  nerves  from  gang- 
lions in  the  same  way  with  them,  it  is  allow- 
able to  infer  that  they  bear  the  same  relation  to 
the  brain  and  spinal  marrow.  Thus  it  would 
appear,  that  the  ganglions  may  be  regarded  as 
a secondary  centre  of  nervous  influence,  receiv- 
ing supplies  from  all  parts  of  the  brain  and 
spinal  marrow,  and  conveying  to  certain  organs 
the  influence  of  all  those  parts. 

If  the  nervous  influence  of  the  thoracic  and  ab- 


188 


dominal  viscera  be  thus  supplied  from  a common 
source,  why,  in  affections  of  the  spinal  marrow, 
it  may  be  said,  is  the  breathing  most  affected 
when  the  disease  is  in  the  dorsal  portion  of  this- 
organ,  and  the  action  of  the  bladder  and  rectum 
most  affected  when  its  chief  seat  is  in  the  lumbar 
portion  ? This  arises  from  the  muscles  of  respira- 
tion deriving  their  nerves  from  the  dorsal  portion, 
and  the  abdominal  muscles  deriving  their  nerves 
from  the  lumbar  portion  of  the  spinal  marrow. 
The  latter  muscles  generally  excite,  or  at  least 
increase,  the  action  of  the  bladder  and  rectum, 
by  pressing  them  against  their  contents,  and  also 
by  this  pressure  contribute  mechanically  to  expel 
their  contents.  Thus,  in  the  above  cases,  in  ad- 
dition to  the  failure  of  nervous  influence  in  the 
viscera,  there  is  a failure  of  excitement  in  the 
muscles  of  voluntary  motion,  which  conspire  with 
these  viscera  in  certain  parts  of  their  functions. 

We  can  trace  the  communications  of  nerves  is- 
suing from  the  great  chain  of  ganglions,  placed, 
it  would  seem,  to  facilitate  these  communications 
in  the  centre  of  the  animal  system,  with  all  the 
nerves  of  the  body.  And  many  circumstances, 
regarded  by  anatomists  as  anomalous,  namely, 
nerves  becoming  larger  after  they  appear  to  send 
off  branches,  apparently  taking  a retrograde 
course,  &c.  are  readily  explained,  if  we  admit 
that  nerves,  arising  from  ganglions,  join  and  again 
separate  from  those  proceeding  in  an  opposite 


189 


direction  from  the  brain  and  spinal  marrow.  It 
is  worthy  of  remark  that  none  of  these  anomalous 
appearances  are  observed  in  the  lower  parts  of 
the  body  and  inferior  extremities,  where  the 
ganglian  must  take  the  same  course  with  the  other 
nerves.  Bichat,  although  his  opinions  respecting 
the  use  of  the  ganglions  are  very  different  from 
those  which  I have  been  led  to  form,  and  indeed 
wholly  inconsistent  with  the  results  of  the  fore- 
going experiments,  was  induced  from  his  obser- 
vation of  the  situation  and  distribution  of  the 
ganglions  and  their  nerves,  to  regard  them  as  the 
centres  of  minute  nervous  systems. 

Comparing  all  that  has  been  said,  we  have 
reason  to  believe,  that  the  system  of  ganglian 
nerves  is  quite  as  extensive  as  that  of  the  nerves 
proceeding  directly  from  the  brain  and  spinal 
marrow.  We  every  where  find  blood  vessels, 
which  we  have  seen  receive  the  nervous  influence 
through  the  ganglions  ; and,  indeed,  in  the  larger 
vessels,  we  can  often  trace  the  ganglian  nerves 
attached  to  and  supplying  them.  The  following 
case,  related  by  Dr.  Parry,  in  the  139th  page  of 
his  Treatise  on  the  Arterial  Pulse,  might  alone 
be  regarded  as  proving  the  existence  of  two  sets 
of  nerves  in  the  extremities  ; the  one  supplying 
the  muscles  of  voluntary  motion,  the  other,  the 
powers  supporting  the  circulation  ; and  striking- 
ly illustrates  what  has  been  said  on  this  subject. 
u I have  seen,”  he  observes,  “ a total  loss  of  pulse 


190 


m one  arm  with  coldness,  but  complete  power 
of  motion  in  that  part ; while  the  other  arm  was 
warm,  and  possessed  a perfectly  good  pulse,  but 
had  lost  all  power  of  voluntary  motion.” 

From  the  foregoing  observations  the  question 
arises,  for  what  purpose  has  nature  thus  combined 
the  influence  of  every  part  of  the  brain  and  spi- 
nal marrow  to  bestow  it  on  particular  parts  ? 
This  question  appears  to  be  answered  by  the  ex- 
periments which  shew,  that  when  the  influence 
of  any  considerable  part,  either  of  the  brain  or 
spinal  marrow,  is  withdrawn  from  secreting  sur- 
faces, the  secreting  power  is  deranged.  This 
we  have  seen  ascertained  by  repeated  experi- 
ments, both  with  respect  to  the  surface  of  the 
stomach  and  lungs.  Among  the  secretions  I 
ranked  the  evolution  of  caloric,  although  not  tak- 
ing place  on  any  particular  surface,  because  it 
appeared  to  be  performed  by  the  same  power 
acting  on  the  same  fluid  ; and  because,  like  se- 
creted fluids,  it  fails  when  any  considerable  part 
of  the  influence  of  the  brain  or  spinal  marrow  is 
withdrawn. 

Admitting,  it  may  be  said,  that  the  due  per- 
formance of  secretion  requires  the  united  power 
of  all  parts  of  the  brain  and  spinal  marrow,  and 
that  we  may,  therefore,  explain  why  their  united 
influence  is  bestowed  on  secreting  surfaces  ; the 
question  still  remains,  why  should  their  united 
influence  be  bestowed  also  on  the  muscles  of  in- 
voluntary motion  ? 


191 

It  is  evident  that  there  could  be  no  occasional 
increase  of  the  secretions,  were  not  the  sangui- 
ferous system  capable  of  being  stimulated  by  the 
same  influence  which  operates  in  the  formation  of 
the  secreted  fluids.  The  increase  of  secreting 
power  in  any  part  would  be  in  vain,  were  there 
not  at  the  same  time  a corresponding  increase  in 
the  supply  of  the  fluids  on  which  it  operates.  A 
similar  observation  applies  to  the  excretory  mus- 
cles as  far  as  they  are  muscles  of  involuntary  mo- 
tion. The  same  increase  of  nervous  influence 
which  occasions  an  increased  flow  of  secreted 
fluids,  excites  these  muscles  to  carry  off  the  in- 
creased quantity.  Nature  does  not  seem  to  trust 
this  to  the  increase  of  stimulus  occasioned  by  the 
increased  flow  of  the  secreted  fluid,  which  we 
have  reason  to  believe  from  the  modus  operandi 
of  certain  causes  of  inflammation,  would  often  oc- 
casion morbid  distension.*  Is  it  not  more  than 
probable  that  the  same  laws  obtain  in  the  absor- 
bent system  ? Now,  the  vascular  system  and  the 
muscles  of  excretion,  if  in  them  we  include  the 
alimentary  canal,  comprehend  all  the  muscles 
which  are  supplied  with  nerves  from  the  gang- 
lions, unless  we  regard  the  iris  as  a muscle. 
The  state  of  this  organ  is  quite  anomalous  in  the 
animal  ceconomy,  being  one  of  involuntary  mo- 
tion, always  stimulated  through  the  medium  of 
the  nervous  system. 

* See  Chap.  XII.  art.  Inflammation. 


192 


Thus,  we  see  the  necessity  of  every  part  of  the 
function  which  the  ganglions  appear  to  perform. 
A combination  of  the  whole  nervous  influence  is 
necessary  for  the  clue  formation  of  the  secreted 
fluids,  and  that  there  may  be,  under  all  circum- 
stances, both  a due  supply  of  the  fluids  to  be 
acted  upon,  and  a due  removal  of  those  prepared, 
whether  for  the  functions  of  life  or  for  the  pur- 
pose of  being  thrown  out  of  the  system,  it  is 
necessary,  as  appears  from  what  has  just  been 
said,  that  the  muscles  which  answer  these  pur- 
poses should  be  subjected  to  the  influence  by 
which  the  secreted  fluids  are  prepared.*  The 
function  of  secretion,  it  is  evident,  requires  a 
more  regular  supply  of  fluids  than  could  have 
been  obtained,  had  the  usual  action  of  the  vessels 
depended  on  the  nervous  system,  which  is  sub- 
ject to  continual  variation ; but  had  not  this  sys- 
tem been  capable  of  stimulating  the  vessels,  no 
change  in  it  could  have  occasioned  an  increased 
flow  of  secreted  fluids.  Thus,  it  is  necessary  that 
the  pow  er  of  the  sanguiferous  should  be  inde- 
pendent of  the  nervous  system,  yet  capable  of  be- 
ing influenced  by  it ; as  it  is  ascertained  to  be 

* The  constant  presence  of  fluids  in  secreting  surfaces  ap- 
pears to  solicit  a continual  supply  of  nervous  influence  to 
them,  so  that  they  go  on  during  our  sleeping  as  well  as  wak- 
ing hours.  The  more  copious  the  supply  of  fluids  to  secret- 
ing surfaces,  we  find  the  secreting  power  the  greater,  and 
vice  versa. 


193 


by  the  experiments  related  in  the  first  and  second 
chapters  of  the  present  part  of  this  Treatise. 

That  the  reader  may  see  how  far  the  observa- 
tions of  the  anatomist  correspond  with  the  result 
of  the  preceding  experiments,  I shall  beg  leave 
to  recall  to  his  mind  the  nervous  connections  of 
the  ganglions  ; by  which  he  will  find  that  they 
may  receive  the  influence  of  every  part  of  the 
brain  and  spinal  marrow,  and  communicate  that 
influence  to  every  part  of  the  body.  The  great 
sympathetic  nerve  receives  nerves  from  every 
part  of  the  spinal  marrow,  being  largest  near  the 
middle  of  the  spine,  and  becoming  smaller  as  it 
ascends  and  descends,  forming  ganglia,  which  give 
out  nerves  on  all  sides.  When  these  circum- 
stances  are  compared  with  the  fact  of  its  convey- 
ing the  influence  of  every  part  of  the  spinal  mar- 
row, we  cannot,  I think,  hesitate  to  regard  it  as 
arising  from  this  organ ; especially  as  its  slender 
communications  with  the  nerves  of  the  head  pre- 
sent the  appearance  of  its  gradual  termination  in 
that  direction.  This  inference  is  further  strength- 
ened by  other  means  being  provided  for  convey- 
ing the  influence  of  the  brain  to  the  thoracic  and 
abdominal  viscera.  The  par  vagum  of  the  eighth 
pair  of  nerves,  we  have  seen  from  the  effects  of 
dividing  it,  performs  this  office ; for  which  it  is 
admirably  fitted,  by  its  numerous  and  extensive 
communications  with  the  ganglions  and  plexuses 

27 


19i 


of  the  great  sympathetic.  After  various  connec- 
tions with  those  in  the  neck  and  chest,  it  sends 
a large  branch  to  the  stomach,  whose  filaments 
are  intermixed  on  this  organ  with  those  of  nerves 
sent  by  several  of  the  abdominal  plexuses ; and 
at  length  terminates  in  forming  with  the  splanch 
nic  branches  of  the  sympathetic  the  great  semilu- 
nar ganglion,  called  the  caeliac  ganglia  from  its 
situation,  and  its  being  composed  of  many  small, 
irregularly  shaped  ganglions  of  different  sizes. 
From  these  ganglions,  so  formed,  mauy  nerves 
issue,  forming  plexuses  on  the  different  large  ar- 
teries, from  which  they  derive  their  names. 
Nerves,  from  these  plexuses  alone,  or  intermixed 
with  other  branches  from  the  sympathetic  nerves, 
supply  the  whole  abdominal  viscera. 

Before  the  sympathetic  nerves  finish  their 
course  by  uniting  on  the  os  coccygis,  they  form 
ganglions  in  the  loins,  which  send  branches  to 
the  lumbar  nerves  ; and  others  in  the  pelvis, 
which  send  branches  to  the  sacral  nerves ; thus 
forming  communications  between  the  ganglian 
system  and  the  nerves  of  the  lower  extremities. 

The  nerves  of  the  upper  extremities  commu- 
nicate with  this  system,  both  by  means  of  the 
middle  cervical  ganglion,  and  through  the  sym- 
pathetic nerves,  by  branches  from  the  second 
and  third  intercostal  nerves  which  go  to  these 
extremities. 

The  ganglian  system  communicates  by  branches 


495 


of  the  sympathetic  nerves  with  the  internal  nerves 
of  the  head.  One  branch  is  sent  to  the  second 
branch  of  the  fifth  pair  before  it  leaves  the  cra- 
nium, and  one,  two,  or  sometimes  three,  small 
filaments  to  the  sixth  pair,  and  a branch  to  the 
portio  dura  of  the  seventh  pair,  at  the  under 
part  of  the  ear.  These  connecting  branches  are 
generally  regarded  as  proceeding  from  the  nerves 
of  the  head,  but  for  reasons  already  assigned,  we 
must,  as  far  as  I am  capable  of  judging,  agree 
with  those  writers  who  regard  them  as  proceed- 
ing from  the  sympathetic  nerves.  The  extensive 
connections  of  those  nerves  with  the  eighth  pair 
have  already  been  mentioned. 

The  external  nerves  of  the  head  and  neck, 
namely,  the  higher  spinal  nerves,  communicate 
with  the  cervical  ganglions  ; and  lastly,  the  gang^ 
lian  system  communicates  with  the  external  parts 
of  the  trunk  by  means  of  the  connections  of  the 
sympathetic  with  the  spinal  nerves  which  supply 
those  parts.* 

Thus,  the  sympathetic  nerves,  conveying  the 
influence  of  the  spinal  marrow,  and  the  par 
vagum,  that  of  the  brain,  unite  in  forming  the 
ganglions,  which  with  their  plexuses,  constitute 

* Here  we  have  reason  to  believe  a double  communication 
takes  place,  the  spinal  nerves  conveying  to  the  sympathetic 
the  influence  of  the  spinal  marrow,  and  the  sympathetic  send- 
ing with  them  to  the  parts  to  which  they  are  distributed, 
filaments  conveying  the  influence  of  the  ganglian  system. 


196 


a secondary  centre  of  nervous  influence,  a chan- 
nel through  which  the  influence  of  every  part  of 
the  brain  and  spinal  marrow  flows,  to  be  be- 
stowed on  the  thoracic  and  abdominal  viscera, 
on  the  vessels  and  all  secreting  surfaces ; the 
most  important  of  which  parts,  we  have  by  di- 
rect experiment  found  subjected  to  every  part 
of  the  brain  and  spinal  marrow. 

In  one  of  the  treatises  referred  to  in  the  Report 
of  the  National  Institute  of  France,  that  by  Dr. 
Johnstone,  the  reader  will  find  many  facts  respect- 
ing the  ganglions  and  the  distribution  of  their 
nerves,  which  he  collected  with  much  assiduity 
for  the  purpose  of  supporting  his  opinions  re- 
specting the  uses  of  these  organs.  He  adopted 
the  opinion  of  Winslow  and  other  physiologists, 
that  the  “ ganglions  seem  analogous  to  the  brain 
in  their  office  ; subordinate  springs  and  reservoirs 
of  nervous  power,”  he  continues, i(  they  seem  ca- 
pable of  dispensing  it,  long  after  all  communica- 
tion with  the  brain  is  cut  off.  And,  although  they 
ultimately  depend  on  the  brain  for  its  emanations, 
it  appears  from  facts,  that  dependence  is  far  from 
being  immediate  and  instantaneous.”*  The  rea- 
der will  readily  perceive  that  this  opinion  is  in 
compatible  with  many  of  the  facts  which  have  been 

* Med.  Essays  and  Obs.  by  J.  Johnstone.  M.  D.  Physi- 
cian in  Worcester,  1795,  p.  85. 


197 

laid  before  him.  Dr.  Johnstone  was  led  to  infer 
that  the  ganglions  can,  for  a certain  time,  perform 
the  office  of  the  brain,  by  ascribing  to  the  power 
of  nervous  influence  many  phenomena  which  seem 
wholly  to  depend  on  the  power  of  the  muscular 
fibre  itself.* 

To  the  above  opinion,  adopted  from  his  prede- 
cessors, Dr.  Johnstone  added  the  following  opi- 
nion of  his  own,  which  he  endeavours  to  support 
by  direct  experiment,  as  well  as  by  an  accurate 
and  extensive  review  of  the  phenomena  of  the 
nervous  system.  “ May  we  not  reasonably  con- 
clude,” he  observes,  “ that  ganglions  are  the  in- 
struments by  which  the  motions  of  the  heart  and 
intestines  are  from  the  earliest  to  the  latest  pe- 
riods of  animal  life  rendered  uniformly  involun- 
tary ?”  f 

Dr.  Johnstone’s  experiments,  an  account  of 
which  is  given  in  the  25th  and  following  pages 
of  the  work  just  quoted,  and  other  experiments 
of  a similar  nature  to  Avhich  he  refers,  of  Haller, 
Whytt,  &c.  were  made  with  a view  to  prove  that 
it  is  impossible  to  affect  the  action  of  the  heart  by 
stimuli  applied  to  the  brain  and  spinal  marrow. 
These  physiologists  appear  to  have  been  deceived 
in  the  result  of  their  experiments  on  this  subject 
by  two  circumstances.  They  did  not  employ  the 

* Chap.  VI. 

t The  above-mentioned  Treatise,  p.  16. 


198 


precaution  of  preventing  the  action  of  the  muscle* 
of  voluntary  motion,  which  renders  it  impossible 
to  judge  of  the  effect  of  the  stimulus  on  the  heart : 
and  they  were  not  aware  that  the  heart  will  not 
obey  a stimulus  applied  to  the  brain  and  spinal 
marrow,  however  powerful,  unless  it  be  applied 
to  a portion  of  considerable  extent.  Any  person 
who  attends  to  these  precautions  will  find,  that 
the  heart  is  not  only  as  easily  stimulated  through 
the  brain  and  spinal  marrow  as  the  muscles  of  vo- 
luntary motion ; but  that  it  may  be  stimulated 
through  them  for  a considerable  time  after  these 
muscles  can  no  longer  be  influenced  in  this  way; 
proving  that  the  ganglions  oppose  no  obstacle  to 
the  influence  of  the  brain  and  spinal  marrow,  be- 
ing extended  to  the  muscles  of  involuntary  mo- 
tion. 

We  can  surely  be  at  no  loss  to  account  for  the 
action  of  these  muscles  being  involuntary,  when 
we  know  that  they  are  all  exposed  to  the  constant 
or  constantly  renewed  action  of  stimuli,  over 
which  the  will  has  no  power.  Besides,  the  ac- 
tion of  these  muscles  produces  no  sensible  effect. 
We  will  to  move  a limb,  not  to  excite  a muscle. 
We  wish  to  handle,  for  example,  and  on  trial 
find  that  we  can  move  our  fingers;  but  what  act 
of  volition  can  we  perform  through  the  medium  of 
the  heart  or  blood  vessels  ? If  we  had  no  wish 
to  handle,  the  muscles  of  the  fingers  of  course 
would  never  become  subject  to  the  will.  It  de- 


199 


serves  to  be  remarked,  that  the  will  influences 
the  rectum  and  bladder,  the  only  internal  organs 
which  can  assist  in  accomplishing  an  end  desired. 

It  seems  to  be  superfluous  after  the  experiments 
which  have  been  related,  to  say  any  thing  in  re- 
futation of  the  opinion  of  Bichat,  and  that  the 
ganglions  are  centres  of  nervous  influence,  inde- 
pendent of  the  brain  and  spinal  marrow.  “ Les 
nerfs  des  ganglions  ne  peuvent  transmettre  l’ac- 
tion  cerebrale ; car  nous  avons  vu  que  le  systeme 
nerveux  partant  de  ces  corps,  doit  etre  considere 
comme  parfaitement  independant  du  systeme  ner- 
veux cerebral ; que  le  grand  sympathique  ne  tire 
point  son  origine  du  cerveau,  de  la  moelle  epini- 
ere  ou  des  nerfs  de  la  vie  animale  ; que  cette  ori- 
gine est  exclusivement  dans  les  ganglions ; que 
ce  nerf  n’existe  meme  point,  a proprement  par- 
ler,  qu’il  n’est  qu’un  ensemble  d’autant  de  petits 
systemes  nerveux  qu’il  y a de  ganglions,  lesquels 
sent  des  centres  particulars  de  la  vie  organique, 
analogues  au  grand  et  unique  centre  nerveux  de 
la  vie  animale,  qui  est  le  cerveau.”  Recherches 
Pliysiologiques  sur  la  vie  et  la  mort  par  Xav. 
Bichat,  page  355  & seq. 


200 


CHAP.  X. 

On  the  relation  which  the  different  functions  of 
the  animal  body  bear  to  each  other,  and  the  or- 
der in  which  they  cease  in  dying. 

It  is  evident  that  before  we  can  attempt  to  trace 
the  relation  which  the  functions  bear  to  each 
other,  and  the  order  in  which  they  cease  in  dy- 
ing, we  must  be  able  clearly  to  define  them.  It 
appears  from  the  experiments  which  I have  had 
occasion  to  relate  or  refer  to,  that  iu  the  more 
perfect  animals  there  are  three  vital  powers  not 
directly  depending  on  each  other,  the  sensorial, 
the  nervous  and  the  muscular  powers. 

With  regard  to  the  last  of  these,  it  is  readily 
distinguished  by  its  effects  from  the  nervous  and 
sensorial  powers,  and  depends,  we  have  seen,  on 
the  mechanism  of  the  muscular  fibre  itself.* 
When  the  mechanism  of  that  fibre  is  deranged, 
its  power  is  destroyed ; and  nothing  else  can  de- 
stroy it. 

The  nervous  power,  it  appears,  from  many  of 
the  experiments  which  have  been  related,  acts 
only  as  a stimulus  to  the  muscular  fibre.  It  per- 
forms the  more  complicated  functions  of  preparing 
the  various  secreted  fluids,  and  causing  an  evo- 


Chap.  III.  and  VI. 


201 


lution  of  caloric  from  the  blood ; and  is  the  means 
by  which  impressions  are  conveyed  to  the  sen- 
sorium. 

The  sensorial  power,  as  far  as  it  is  concerned  , 
in  the  functions  of  mere  animal  life,  appears  to 
consist  wholly  in  receiving  impressions  from,  and 
communicating  them  to  the  nervous  power. 

The  seat  of  the  sensorial  and  nervous  powers 
is  not  so  well  defined  as  that  of  the  muscular 
power.  M.  le  Gallois  appears  to  regard  the 
brain  as  the  seat  of  the  one,  and  the  spinal  mar- 
row as  that  of  the  other ; but  many  observations 
seem  to  oppose  this  opinion.  Nerves  proceeding 
wholly  from  the  brain  exhibit  all  the  phenomena 
of  nervous  power,  properly  so  called ; and  that  the 
spinal  marrow  possesses  sensorial  power  appears 
from  very  simple  experiments. 

Exp.  72-  If,  after  the  spinal  marrow  of  a rab- 
bit is  divided  about  the  middle,  one  of  the  hind 
legs  be  wounded,  not  only  the  wounded  leg  is 
moved,  but  the  other  hind  leg  also,  demonstrating 
that  there  is  a power  residing  in  the  spinal  mar- 
row which  receives  the  impression  made  on  the 
nerves  of  the  one  leg  and  communicates  it  to  those 
of  the  other.  M.  le  Gallois  makes  many  similar 
observations.  In  the  cold  blooded  animal  the 
same  thing  is  observed  in  a greater  degree.  For 
some  hours  after  decapitation  the  frog  will  often 
sit  in  its  usual  position,  and  appear  sensible  to  an 
injury  inflicted  on  any  part  of  it.  It  is  evident 

28 


202 


from  many  observations,  however,  that  the  sen- 
sorial power  chiefly  resides  in  the  brain,  and  the 
nervous  in  the  spinal  marrow. 

If  these  powers,  it  may  be  said,  are  thus  blend- 
ed in  their  organs,  what  proof  have  we  of  their 
being  distinct  powers  ? This  proof  I think  we 
shall  find  by  carefully  observing  the  process  of 
dying,  of  which,  what  we  call  death  appears  to 
be  only  the  first  stage.  We  shall  also,  I think, 
by  the  same  means,  clearly  perceive  the  way  in 
which  all  the  foregoing  powers  are  so  connected 
in  the  more  perfect  animals,  that  none  can  long 
exist  without  the  others. 

At  the  instant  of  death,  it  is  evident,  the  sen- 
sorial power  ceases.  No  impression  made  on 
any  part  of  the  body  is  perceived  or  followed  by 
any  act  of  volition.  It  is  equally  evident  to  the 
physiologist  that  the  muscular  power  still  re- 
mains. If  the  heart,  or  muscles  of  voluntary 
motion  be  stimulated,  they  still  possess  the  pow- 
er of  contraction,  which  is  only  lost  by  slow  de- 
grees, a considerable  time  after  the  sensorial  pow- 
er has  ceased  to  exist.  It  is  also  evident  to  the 
physiologist,  that  some  part  of  the  nervous  power 
still  exists,  for  if  the  nerves  themselves,  or  those 
parts  of  the  brain  or  spinal  marrow  from  which 
they  originate,  be  irritated,  the  corresponding 
muscles  are  thrown  into  action  ; a proof  that  the 
extinction  of  the  sensorial  powers  does  not  de- 
pend on  the  nerves  having  become  incapable  of 


203 


conveying  impressions.  Is  the  nervous  power 
still  capable  of  performing  its  other  functions? 
Whether  it  is  capable  of  conveying  impressions 
to  the  sensorium  we  have,  of  course,  no  means  of 
judging,  where  no  sensorium  exists;  but  if  we 
find  it  capable  of  all  its  other  functions,  we  may 
infer  that  it  possesses  this  function  also,  and  that 
the  cause  of  its  non-appearance  is  the  known  fail- 
ure of  the  power  which  must  conspire  to  make 
this  part  of  its  functions  sensible.  The  question 
then  which  we  have  to  consider  here  is,  can  the 
nervous  power  effect  the  formation  of  the  secreted 
fluids,  and  occasion  an  evolution  of  caloric  from 
the  blood,  as  we  find  it  can  excite  the  muscles,  af- 
ter the  destruction  of  the  sensorial  power  ? 

I have  already  had  occasion  to  refer  to  Mr. 
Hunter’s  observations  respecting  the  digestion  of 
the  stomach  after  death.  It  is  perhaps  superflu- 
ous to  observe,  that  this  is  not  to  be  regarded  as 
any  vital  action.  It  is  a mere  chemical  process. 
But  Mr.  Hunter,  as  appears  from  the  following 
observations,  suspected  that  a truly  vital  action 
continues  in  the  stomach  for  some  time  after  what 
is  called  death.  u This  is  exactly  the  case  with 
the  experiments  of  Spallanzani,  which  although 
they  prove  that  meat  was  digested  in  the  stomach 
after  the  animal  was  killed,  which  no  one  doubt- 
ed,” that  is,  no  one  doubted  that  the  gastric  juice 
already  in  the  stomach  would  continue  to  perform 
its  office  there,  u yet  are  not  at  all  calculated  to 


204 


shew  that  the  stomach  itself  may  be  digested; 
In  fact  the  manner  in  which  they  were  managed 
rather  tended  to  prevent  that  effect  from  taking 
place,  the  gastric  juice  having  substances  intro- 
duced on  which  it  could  act,  was  less  likely  to 
affect  the  coats  of  the  stomach.  That  the  diges- 
tion was  not  carried  on  merely  by  the  effects  of 
the  gastric  juice  secreted  before  death,  is  evident 
from  his  own  account,  some  of  the  food  which 
had  been  introduced  and  digested  being  found 
in  the  duodenum ; a thing  which  could  not  have 
happened  if  a cessation  of  the  actions  of  life  in 
the  involuntary  parts  had  taken  place  when  visi- 
ble life  terminated.  There  had  been  an  action 
and  most  probably  a secretion  in  the  stomach”* 
It  appeared  to  me  that  this  conjecture  of  Mr. 
Hunter  might  be  reduced  to  the  test  of  experi- 
ment, by  dividing  immediately  after  death  the 
eighth  pair  of  nerves,  which  seems  at  once  to 
destroy  the  secretion  of  gastric  juice.  I shall 
use  the  words  death  and  killed  in  the  usual  ac- 
ceptation, not  implying  the  ceasing  of  all  the 
functions.  After  this  explanation  no  ambiguity 
can  arise  from  the  use  of  these  terms.  We  are 
not,  it  is  evident,  to  expect  that  any  great  secretion 
of  gastric  juice  can  take  place  after  death,  or  conse- 
quently that  any  great  difference  can  be  observed 
between  the  food  in  the  stomach  of  an  abimal 


Observations  on  the  Animal  (Economy,  page  181. 


205 


in  which  the  eighth  pair  of  nerves  has  been  di- 
vided immediately  after  death,  and  one  in  which 
they  are  left  entire ; and  many  circumstances  which 
we  cannot  estimate,  particularly  there  being  more 
gastric  juice  in  the  stomach  of  the  one  animal 
than  the  other,  at  the  time  they  are  killed,  or  one 
having  eaten  more  than  the  other,  must  influence 
the  result.  It  will  not  answer  the  purpose,  it  is 
evident,  to  confine  the  animals  to  the  same  quan- 
tity of  food,  because  the  stomach  of  that  which  is 
most  hungry  will  digest  it  most  quickly.  The 
quantity  of  old  food  in  the  stomach  also  influ- 
ences the  result.  The  question,  therefore,  can 
only  be  determined  by  making  the  experiment 
on  a large  scale,  to  which,  as  it  is  made  on  the 
dead  animal,  there  can  be  no  objection. 

Exp.  73.  This  experiment  was  made  on  twen- 
ty-six rabbits  ; eight  full  grown,  eight  half  grown, 
six  two  months  old,  and  four  one  month  old. 
They  were  made  to  fast  for  sixteen  hours,  at  the 
end  of  this  time  allowed  to  eat  as  much  cabbage 
as  they  chose,  and  then  killed  by  a blow  on  the 
occiput.  Immediately  after  death  the  eighth  pair 
of  nerves  was  divided  in  one  half  of  those  of 
each  description,  and  they  were  all  allowed  to  lie 
undisturbed  for  about  twenty-two  hours.  I need 
hardly  observe  that  the  experiment  was  not  made 
on  all  at  the  same  time,  but  care  was  taken  that 
the  circumstances  of  it  should  be  the  same  in  all. 
The  stomachs  were  then  laid  open,  and  those  of 


206 


the  rabbits  of  the  same  age,  who  had  eaten  most 
nearly  the  same  quantity,  were  compared  together. 
The  result  was,  that  in  twelve  pairs  the  food  was 
most  digested  in  those  animals  whose  nerves  were 
left  entire.  In  one  pair  it  was  most  digested  in 
the  animal  whose  nerves  had  been  divided.  In 
several  of  those  whose  nerves  had  been  divided, 
the  cabbage  appeared  quite  fresh  and  green. 
This  did  not  happen  iu  any  whose  nerves  were 
left  entire.  In  these  the  colour  was  alwavs  chang- 
ed  more  or  less  to  a brown.  The  difference  in 
the  state  of  the  cabbage  was  sometimes  more  sen- 
sible to  the  touch  than  to  the  eye,  that  least  digest- 
ed feeling  hardest.  This  experiment,  at  the  same 
time  that  it  proves  the  accuracy  of  Mr.  Hunter's 
conjecture,  shews  more  than  any  experiment 
made  on  the  living  animal  could  do,  how  quickly 
the  secretion  of  gastric  juice  is  destroyed  by  the 
division  of  the  eighth  pair  of  nerves  in  the  neck. 

It  is  remarkable  that  the  division  of  these  nerves 
after  death  almost  always  produced  the  same  ap- 
pearance of  dark  coloured  patches  upon  the  sur- 
face of  the  lungs,  but  generally  in  a less  degree, 
observed  from  it  when  the  operation  had  been  per- 
formed during  the  life  of  the  animal : an  effect, 
equally  with  the  state  of  the  stomach,  demon- 
strating that  some  of  the  involuntary  functions 
continue  for  a certain  time  after  visible  death. 
These  patches  now  and  then  appear  in  the  lungs 
of  an  animal  whose  nerves  are  entire,  after  it  has 


207 


lain  dead  for  some  time ; but  much  less  frequent- 
ly, and  to  a much  less  degree,  than  when  the 
nerves  have  been  divided  immediately  after  death. 

The  appearance  of  dark  red  patches  on  the 
surface  of  the  lungs,  we  have  seen,  is  always  ob- 
served to  a great  degree  when  the  eighth  pair  of 
nerves  have  been  divided  during  the  life  of  the 
animal,  and  it  has  survived  the  operation  many 
hours.  It  may  be  regarded,  and  is  mentioned  by 
various  physiologists,  as  the  characteristic  effect 
of  the  operation  on  this  organ.  The  congestion 
of  the  lungs,  which  is  also  an  uniform  conse- 
quence of  it,  appears  under  many  other  circum- 
stances, but  I know  of  no  other  in  which  there  is 
an  appearance  like  this  patching,  except,  as  I 
have  just  mentioned,  that  a certain  degree  of  it,  or 
rather  something  like  it,  now  and  then  appears 
in  the  lungs  of  the  entire  animal  after  it  has  lain 
dead  for  many  hours.  In  the  living  animal  it 
was  always  proportioned  to  the  degree  in  which 
the  secreting  power  of  the  lungs  was  deranged, 
appearing  to  the  greatest  degree  when  the  con- 
gestion of  the  lungs  was  greatest ; and  not  ap- 
pearing at  all,  although  the  eighth  pair  of  nerves 
had  been  divided,  when  the  breathing  was  ren- 
dered free,  and  the  congestion  prevented  by  gal- 
vanism. 

Exp.  74.  It  was  suggested,  that,  by  the  power 
of  galvanism  the  degree  of  digestion  which  takes 
place  after  death  might  perhaps  be  increased. 


But  we  could  not  by  any  means  cause  the  gal- 
vanism to  produce  any  sensible  effect  on  the  rab- 
bit after  death,  except  for  a very  short  time; 
sometimes  no  effect  could  be  produced  longer 
than  five  minutes,  and  in  no  instance  was  the  ef- 
fect sensible  beyond  about  a quarter  of  an  hour, 
even  with  the  assistance  of  artificial  respiration 
and  a very  powerful  galvanic  apparatus  ; and 
during  these  short  times  its  effects  were  constant- 
ly becoming  weaker.  We  could  never  even  suc- 
ceed in  producing  the  slightest  appearance  of  in- 
flammation either  in  the  stomach  or  bowels,  an  ef- 
fect which  uniformly  attends  digestion  supported 
by  galvanism.  From  these  circumstances,  and 
from  what  I have  said  above,  respecting  the  dif- 
ficulty of  ascertaining  whether  or  not  a slight  ad- 
ditional degree  of  digestion  has  taken  place,  I 
need  hardly  say,  that  it  was  impossible  to  ascer- 
tain whether  or  not  any  change  on  the  food  was 
effected  in  this  experiment. 

I think  there  is  reason  to  believe,  that  although 
the  galvanic  influence  could  be  supported  for  a 
longer  time  after  death,  it  would  occasion  no  in- 
crease of  secretion.  No  inflammation  occurring 
seems  to  arise  from  there  being  no  increase  of  vis 
a tergo,  that  is,  no  increased  action  in  the  larger 
vessels.  Thus,  whatever  increase  of  nervous  in- 
fluence there  may  be,  there  can  be  no  increased 
supply  of  fluids  for  it  to  act  upon,  without  which 
it  is  evident  there  can  be  no  increased  secretion 


209 


What  then,  it  may  be  asked,  occasions  any  sup- 
ply of  fluids  to  secreting  surfaces,  and  thus  ena- 
bles the  remaining  nervous  influence  to  produce 
any  secreted  fluid  after  death  ? The  result  of  the 
following  experiment  appears  to  afford  a ready 
answer  to  this  question. 

Exp.  75.  A rabbit,  about  two  months  old, 
was  killed  by  a blow  on  the  occiput.  The  chest 
was  then  laid  open  and  a ligature  thrown  round 
the  aorta.  Part  of  the  mesentery  was  now  brought 
before  a microscope,  and  the  blood  in  its  vessels 
seen  both  by  Mr.  Sheppard  and  myself,  moving 
with  great  velocity.  By  examining  different 
parts  of  it,  and  chusing  those  which  had  not  been 
previously  disturbed,  and  consequently  still  re- 
tained some  warmth,  we  found  the  circulation, 
in  the  smaller  vessels,  going  on  with  rapidity 
for  a quarter  of  an  hour  after  the  aorta  had  been 
secured,  and  an  irregular  motion  of  the  blood  in 
these  vessels  was  evident  for  twenty  minutes 
longer,  the  blood  stopping  and  going  on,  and 
sometimes  moving  backwards  and  forwards  in 
the  same  vessel.  This  could  be  distinctly  seen 
long  after  the  part  had  become  quite  cold.  This 
experiment  was  performed  in  the  sun-sliine,  in 
the  open  air,  where  there  happened  to  be  a good 
deal  of  wind,  and  the  exposed  part  of  the  mesen- 
tery quickly  became  parched  ; which,  as  we  found 
from  other  trials,  destroyed  the  motion  of  the 

29 


210 


blood  in  the  capillaries  long  before  it  naturally 
ceases. 

Full-grown  rabbits  are  bad  subjects  for  this 
experiment,  on  account  of  an  accumulation  of  fat 
which  takes  place  in  the  mesentery,  and  obscures 
the  vessels.  Rabbits  about  six  weeks  old,  when 
they  have  been  fed  for  some  time  on  green  meat, 
are  generally  thin,  and  consequently  the  best  sub- 
jects for  it. 

Exp.  76.  A dead  rabbit,  about  a month  old, 
whose  intestines  we  had  been  examining,  after 
having  thrown  a ligature  round  all  the  vessels  at- 
tached to  the  heart  and  removed  this  organ,  was 
thrown  aside,  with  the  intestines  hanging  out 
through  the  wound  in  the  parietes  of  the  abdomen. 
An  hour  and  a quarter  after  the  heart  had  been 
removed,  I brought  part  of  the  mesentery,  which 
had  long  been  quite  cold,  before  the  microscope, 
and  still  found  the  blood  in  some  of  the  capillary 
vessels  moving  freely.  I have  no  doubt  that  the 
blood  continues  to  move  in  the  capillaries  of  a 
full-grown  rabbit,  whose  temperature  will  sink 
much  more  slowly,  for  several  hours  after  death. 
This  at  the  same  time  accounts  for  the  supply  of 
fluids  to  secreting  surfaces,  and  for  a certain  pow- 
er of  the  nervous  system  remaining  after  death, 
and  when  the  vis  a tergo  has  wholly  ceased,  ex- 
cept as  far  as  it  depends  on  mere  elasticity  and 
the  action  of  very  small  vessels.  It’  seems  to  be 


211 


owing  to  this  cause  also  that  the  larger  arteries 
of  dead  animals  are  found  empty.*  How  readily 
the  continued  action  of  the  capillaries  must  empty 
them,  will  be  evident  when  we  recollect  how 
much  the  sum  of  the  areas  of  the  branches  of  the 
arteries  exceeds  the  areas  of  their  trunks.  I need 
not  observe  how  inconsistent  the  result  of  the 
foregoing  experiment  is  with  the  opinion  of  Doc- 
tor Parry,  and  some  other  physiologists,  who 
maintain  that  the  circulation  is  supported  by  the 
power  of  the  heart  alone. 

Exp.  77-  Although  it  is  difficult  to  ascertain 
whether  galvanism  influences  the  state  of  the  sto- 
mach after  death,  the  case  is  very  different  with 
respect  to  the  lungs.  In  them  it  is  easy,  from 
the  degree  of  patching,  with  precision  to  ascer- 
tain the  state  of  the  secretions.  Here,  however, 
there  was  no  occasion  for  minute  observation, 
for  in  nine  instances,  in  which  a stream  of  gal- 
vanism was  sent  through  the  lungs  for  about  a 
quarter  of  an  hour  after  the  eighth  pair  of  nerves 
had  been  divided  immediately  after  death,  all 
appearance  of  patching  was  prevented,  the  lungs 
after  the  animal  had  lain  dead  about  twenty  hours 
appearing  quite  sound. 

It  appears  from  the  foregoing  experiments  that 

* I cannot  agree  with  Dr.  Parry  in  ascribing  this  fact  to 
the  contractility  of  the  arteries.  This  may  reduce,  but  it  can- 
not wholly  expel  their  contents. 


the  secreting  power  continues  for  some  time  after 
the  sensorial  power  has  ceased;  we  are  now  to 
inquire  whether  the  nervous  power,  under  the 
same  circumstances,  is  capable  of  occasioning  an 
evolution  of  caloric  from  the  blood.  I here  con- 
sider it  as  proved  by  experiments  already  laid 
before  the  reader,  that  the  evolution  of  caloric 
is  a function  of  the  nervous  influence.  It  seems 
so  immediately  to  depend  on  the  existence  of  the 
circulation,  and  so  generally  proportioned  to  its 
vigour,  that  we  cannot,  I think,  adopt  a better 
means  of  answering  the  question  before  us,  than 
by  ascertaining  whether  supporting  circulation 
by  artificial  respiration  after  death  occasions  a 
greater  evolution  of  caloric  than  takes  place 
when  the  dead  animal  is  left  undisturbed.  On 
this  subject  there  has  been  great  difference  of 
opinion.  The  following  experiments  seem  to 
point  out  how  this  difference  may  have  arisen, 
on  the  supposition  that  all  the  experiments 
which  have  been  made  on  the  subject  are  correct, 
which  we  have  every  reason  to  believe  them 
to  be. 

Exp.  78.  Two  rabbits  of  the  same  size  were 
killed  by  a blow  on  the  occiput,  the  temperature 
of  the  air  being  61°,  that  of  both  rabbits  104°. 
The  lungs  of  one  were  inflated  six  times,  those 
of  the  other  from  twenty-six  to  thirty  times  in  a 
minute.  The  temperature  of  the  first  in  half  an 
hour  was  10 2.35°,  in  an  hour  100°;  the  tempe- 


213 


ratttre  of  the  second  at  the  end  of  half  an  hour 
was  101.5°,  at  the  end  of  an  hour  98°. 

It  is  evident  that  all  the  air  thrown  into  the 
lungs,  beyond  what  is  necessary  to  effect  the  pro- 
per change  in  the  blood,  must  tend  to  reduce  the 
temperature  in  proportion  as  that  of  the  air  is  less 
than  that  of  the  animal.  The  living  animal  re- 
ceives but  little  air  into  the  lungs  in  one  inspira- 
tion. It  is  impossible  in  the  dead  animal  to 
throw  in  the  quantity  which  the  blood  still  de- 
mands and  no  more. 

The  following  experiments,  in  which  Mr.  Shep- 
pard was  so  good  as  to  assist  me,  as  indeed  he  did 
in  all  the  experiments  which  I made  on  this  part 
of  the  subject,  strikingly  illustrate  these  observa- 
tions. 

Exp.  79.  Two  rabbits  were  chosen  of  the 
same  size,  and  each  of  the  temperature  of  102.5°. 
They  were  killed  in  the  usual  way,  in  the  tempe- 
rature of  65°  ; one  was  left  undisturbed.  In  the 
other,  the  lungs  were  inflated  about  thirty  times 
in  a minute.  In  half  an  hour  the  temperature  of 
the  undisturbed  rabbit  was  98.75°,  while  that  of 
the  other  was  only  98.5°.  In  the  last  the  lungs 
were  then  inflated  only  about  twelve  times  in  a 
minute.  In  half  an  hour  its  temperature  was  96°, 
so  that  it  had  lost  2.5°,  while  that  of  the  other  left 
undisturbed  had  in  the  same  time  sunk  to  95.25°, 
so  that  it  had  lost  3.5. 

Exp.  80.  Two  rabbits  were  killed  in  a tempe- 


214 

rature  of  61. 5.°  The  temperature  of  the  one  was 
106°,  of  the  other  103,  the  lungs  of  the  first  were 
inflated  twelve  times  in  the  minute,  the  other  was 
left  undisturbed.  In  half  an  hour  the  first  had 
lost  3.5°,  its  temperature  being  102.5°.  The 
other  in  the  same  time  had  last  4°,  its  temperature 
being  99°.  The  first  being  of  the  highest  tempe- 
rature, would  have  cooled  fastest  had  both  been 
undisturbed,  although  probably  not  in  a sensible 
degree.  I may  here  observe,  that  it  always  hap- 
pened in  the  course  of  such  experiments  as  those 
which  I am  relating,  that  the  temperature  of  the 
room  varied,  but  as  the  experiment  was  always 
made  on  both  rabbits  at  the  same  time,  and  placed 
together,  this  could  not  influence  the  result,  and 
is  therefore  unnoticed.  The  lungs  of  the  first  of 
the  above  rabbits  were  now  inflated  at  the  rate  of 
from  twenty-six  to  thirty  times  in  a minute.  At 
the  end  of  half  an  hour  its  temperature  was  98°, 
that  of  the  other  at  the  same  time  being  94.5°,  so 
that  each  had  now  cooled  4.5°,  the  evolution  of 
caloric  in  consequence  of  the  inflation  of  the  lungs 
being  here  sufficient  to  counteract  the  cooling  effect 
of  the  rapid  change  of  air,  and  no  more.  In  one 
experiment  of  this  kind,  in  which  the  lungs  were 
inflated  only  a few  times  in  a minute,  we  found 
that  the  temperature  had  risen  nearly  1°  between 
two  of  the  examinations. 

"While  I was  making  experiments  on  this  sub- 
ject in  Worcester,  Mr.  Hastings,  was,  without  my 


21 5 


knowledge,  making  similar  experiments  at  Edin- 
burgh. He  shewed  me  the  detail  of  several, 
which  prove  that  throwing  air  into  the  lungs  of 
the  dead  rabbit  about  fifteen  times  in  a minute, 
occasions  it  to  cool  more  slowly  than  it  would 
otherwise  do.  In  one  of  his  experiments  the 
rabbit,  in  which  artificial  breathing  was  per- 
formed, cooled  only  4°,  while  that  which  was 
left  undisturbed  cooled  7-5°.  This  was  the 
greatest  difference  he  observed.  He  frequently 
saw  the  thermometer  rise  a little  in  those  ani- 
mals in  which  the  lungs  were  inflated  after 
death.  In  those  in  which  they  were  not  inflated 
the  cooling  was  always  uniform. 

There  can  be  no  doubt,  I think,  from  the  pre- 
ceding experiments,  that  when  the  lungs  are  not 
inflated  so  frequently  as  to  constitute  a power- 
fully cooling  process,  their  inflation,  by  occasion- 
ing an  evolution  of  caloric  after  what  we  call 
death,  retards  the  cooling  of  the  animal. 

My  next  object  was  to  ascertain  how  far  the 
evolution  of  caloric,  after  death,  is  influenced  by 
the  destruction  of  the  brain  and  spinal  marrow. 

Exp.  81.  Two  rabbits  of  the  same  size,  whose 
temperature  was  98°,  were  killed  in  the  usual 
way.  In  one,  immediately  after  death,  the  brain 
and  spinal  marrow  were  destroyed  by  introduc- 
ing, through  a hole  in  the  cranium,  a wire  of 
nearly  the  same  diameter  with  the  cavity  of  the 


216 


spine,  repeatedly  pushing  it  on  to  the  end  of  this 
cavity,  and  then  moving  it  about  for  some  time 
in  the  cavity  of  the  cranium.  The  other  rabbit 
was  left  entire.  A hole  was  made  about  the 
centre  of  the  abdominal  muscles  in  each,  to  ad- 
mit of  a thermometer  being  introduced  into  the 
cavity  of  the  abdomen.  They  were  placed  near 
each  other  in  a temperature  of  50°.  During  the 
first  twenty  minutes  each  lost  exactly  4°,  and  they 
both  lost,  during  the  succeeding  three  quarters  of 
an  hour,  just  2°  during  each  quarter.  Something, 
which  we  could  not  ascertain,  accelerated  the  rate 
of  cooling  during  the  next  quarter,  and  so  exactly 
did  it  correspond  in  both  rabbits,  that  each  lost 
during  this  quarter  2.5.  After  this  their  tempe- 
rature diminished  more  slowly,  and  still  more  so 
of  course  as  it  approached  more  nearly  to  that  of 
the  air,  but  still  in  both  it  was  found  to  corres- 
pond. At  the  end  of  a hundred  and  ten  minutes 
the  temperature  of  both  rabbits  was  84°. 

Exp.  82.  The  foregoing  experiment  was  re- 
peated, with  the  difference  that  in  both  rabbits 
the  lungs  were  inflated ; but  we  could  not  per- 
ceive that  the  one  rabbit  cooled  faster  than  the 
other. 

Exp.  83.  Two  rabbits  of  the  same  size  and 
temperature,  being  killed  in  the  usual  way,  in 
the  one  the  brain  and  spinal  marrow  were 
wholly  removed,  the  other  being  left  entire. 


217 


In  both  the  lungs  were  inflated.  We  could  not 
perceive  that  the  one  cooled  faster  than  the  other. 

I was  particularly  careful  in  repeating  these 
experiments,  because  they  appear  at  first  view  to 
contradict  the  inferences  of  Mr.  Brodie,  to  whose 
labours  this  part  of  physiology  owes  so  much.  It 
will  appear,  however,  from  what  I am  about  to 
say,  that  their  result  is  perfectly  consistent  with 
the  doctrine  maintained  by  him. 

It  appears  from  the  foregoing  experiments,  that 
after  the  destruction  of  the  sensorial,  the  nervous 
power  is  still  capable  of  performing  all  its  func- 
tions, except  that  it  can  no  longer  give  evidence 
of  conveying  impressions  to  the  sensorial  power, 
the  necessary  consequence  of  the  destruction  of 
this  power.  On  comparing  these  experiments, 
however,  a considerable  difficulty  presents  itself. 
We  have  seen  it  ascertained  by  those  on  digestion, 
that  the  brain  and  spinal  marrow  retain  sufficient 
power  after  visible  death  to  form  secreted  fluids. 
Yet  it  would  appear  from  the  experiments  on 
temperature,  that  the  influence  of  the  brain  and 
spinal  marrow  has  no  effect  under  the  same  cir- 
cumstances in  promoting  the  evolution  of  caloric, 
although  it  is  evident  that  the  system  still  retains 
the  power  of  evolving  it,  and  from  former  expe- 
riments, that  this  power  depends  on  the  state  of 
the  nervous  system.  The  secreted  fluids  are  no 

longer  formed  if  the  influence  of  the  brain  be  with- 

30 


drawn,  the  evolution  of  caloric  takes  place  in  the 
same  way  whether  the  influence  of  both  the  brain 
and  spinal  marrow  be  withdrawn  or  not. 

A well-known  fact  appears  to  remove  the  dif- 
ficulty. Although  we  have  reason  to  believe,  I 
think,  from  every  observation  on  the  subject,  that 
the  brain  and  spinal  marrow  are  the  only  sources 
of  nervous  influence ; yet  it  is  evident  that  a cer- 
tain portion  of  this  influence  remains  in  the  nerves 
when  separated  from  these  organs,  as  appears 
from  the  contractions  excited  in  the  muscles  by 
irritating  their  nerves  under  such  circumstances. 
The  muscle  will  thus  be  made  to  contract  as 
long  as  any  influence  remains  in  the  nerve,  but 
this  being  once  exhausted,  the  nerve  has  no  means 
of  renewing  it.  Now,  the  first  nervous  influence 
which  is  employed  in  the  stomach  after  death  is 
of  course  that  already  in  its  nerves.  This  being 
exhausted,  the  brain  and  spinal  marrow  are  call- 
ed upon  for  a further  supply.  It  is  evident  that 
they  cannot  be  long  so  called  upon,  because  there 
cannot  long  be  any  supply  of  proper  fluids.  If 
then,  instead  of  the  nerves  which  belong  to  the 
stomach,  the  whole  nerves  of  the  ganglian  sys- 
tem terminated  in  this  organ,  there  is  reason  to 
believe,  that  the  supply  of  fluids,  which  takes 
place  after  death,  would  never  be  sufficient  to  ex- 
haust the  nervous  influence  already  in  its  nerves ; 
and  consequently,  that  in  that  case  it  would  never 
make  any  demand  on  the  brain  and  spinal  mar- 


219 


row ; and  the  same  degree  of  digestion  would 
take  place  after  death  whether  the  influence  of 
the  brain  remained  or  not.  Now  this  is  precisely 
what  seems  to  happen  with  respect  to  the  tempe- 
rature after  death.  As  long  as  we  can  by  artifi- 
cial respiration  occasion  such  a change  in  the 
blood  as  elicits  nervous  influence,  the  blood  draws 
it  from  all  the  nerves  of  the  ganglian  system ; and 
it  does  not  appear,  that  we  can  support  this 
change  long  enough  to  exhaust  the  nervous  in- 
fluence already  in  the  nerves,  and  occasion  any 
further  demand  for  it.  It  appears  from  the  above 
experiments,  that  the  greatest  evolution  of  caloric, 
which  can,  under  ordinary  circumstances,  be  ef- 
fected after  death,  is  but  very  inconsiderable. 
Hence,  the  result  is  the  same  whether  the  brain 
and  spinal  marrow  exist  or  not.  The  blood  has 
already  in  the  nerves  more  nervous  influence 
than  it  can  use.  Hence  also,  as  I have  ascertain- 
ed by  repeated  trials,  we  cannot,  under  these  cir- 
cumstances, occasion  any  additional  evolution  of 
caloric  by  galvanism.* 

The  evolution  of  caloric  occasioned  by  inflating 
the  lungs  after  death  being  so  small,  may  arise 
from  our  being  able  but  very  imperfectly  to  imi- 
tate natural  respiration.  It  is  true  that  we  can  imi- 

* I have  considered  the  cause  of  the  sensation  of  heat  a 
substance  not  a quality,  because  I regard  the  former  as  the 
more  probable  opinion.  I admit  that  some  difficulties  re- 
specting it  exist. 


220 


late  it  sufficiently  to  give  the  arterial  colour  to  the 
blood,  but  we  have  seen  that  the  evolution  of  ca- 
loric does  not  appear  to  be  connected  with  the 
change  of  colour.  It  is  evidently  impossible  to 
proportion  the  quantity  of  air  thrown  in,  to  the 
demand  for  it,  which  is  constantly  becoming  less, 
so  that  we  are  either  supplying  too  much  or  too 
little.  In  the  former  case,  the  superfluous  quan- 
tity can,  as  far  as  relates  to  the  temperature,  have 
no  other  effect  but  that  of  reducing  it,  as  happen- 
ed in  the  above  experiments ; but  although  we 
could  supply  air  in  the  due  proportion,  we  should 
still  be  very  far  from  being  able  to  imitate  natu- 
ral respiration,  from  which  artificial  respiration, 
among  other  things,  differs  in  the  great  pressure 
to  which  the  lungs  are  subjected  in  the  latter,  in 
which  the  ribs  and  diaphragm  are  moved  by  the 
force  of  the  injected  air;  whereas  in  natural  re- 
spiration the  ribs  and  diaphragm  being  moved  by 
their  muscles,  the  lungs  are  subjected  to  no  pres- 
sure but  that  of  the  atmosphere.  The  great  di- 
minution of  nervous  influence  in  artificial  respi- 
ration constitutes  an  essential  difference  between 
it  and  natural  breathing.  It  would  be  worth 
while,  although  attended  with  considerable  trou- 
ble, accurately  to  ascertain  the  effects  of  passing 
a stream  of  galvanism  through  the  lungs  while 
artificial  respiration  is  performed. 

A very  decisive  experiment  by  Mr.  Brodie, 
related  in  addition  to  the  Croonian  Lecture  above 


221 


referred  to,  proves  that  the  change  of  oxygen  gas 
into  carbonic  acid  gas  takes  place  when  the  lungs 
are  inflated  after  decapitation. 

It  remains  for  us  to  inquire  whence  it  arises 
that  the  nervous  and  muscular  powers  never  long 
survive  the  sensorial  power. 

On  the  destruction  of  the  sensorial  power  re- 
spiration always  ceases.  M.  le  Gallois  finds  a 
great  difficulty  in  conceiving  why  respiration 
should  cease  on  the  removal  of  the  brain. 

“ II  est  done  certain  que  la  vie  du  tronc  n’a  son 
principe  immediat  ni  dans  le  cerveau,  ni  dans 
aucun  des  visceres  de  la  poitrine  et  de  Pabdomen ; 
mais  il  ne  Pest  pas  moins,  que  tous  ces  visceres 
sont  indispensables  a son  entretien.  Or,  en  con- 
siderant  sous  quel  rapport  ils  le  sont,  les  faits 
enonces  plus  haut  prouvent  evidemment  que, 
quant  au  cerveau,  les  plienomenes  mechaniques 
de  la  respiration,  e’est-a-dire,  les  mouvemens  par 
lesquels  Panimal  fait  entrer  Pair  dans  ses  pou- 
mons,  dependent  immediatement  de  ce  viscere. 
Ainsi,  e’est  principalement  en  tant  que  Pentretien 
de  la  vie  depend  de  la  respiration,  qu’il  depend 
du  cerveau  ; ce  qui  donne  lieu  a une  grande  diffi- 
culty Les  nerfs  diaphragmatiques,  et  tous  les 
autres  nerfs  de  muscles  qui  servent  aux  pheno- 
menes  mechaniques  de  la  respiration,  prennent 
naissance  dans  la  moelle  6piniere,  de  la  m&me 


maniere  que  ceux  de  tous  les  autres  muscles  du 
tronc.  Comment  se  fait-il  done  qu’apres  la  de- 
capitation, les  seuls  mouvemens  inspiratoires 
soient  aneantis,  et  que  les  autres  subsistent?  C’est 
la,  a mon  sens,  un  des  grands  mysteres  de  la 
puissance  nerveuse ; mystere  qui  sera  devoile  tot 
ou  tard,  et  dont  la  decouverte  jettera  la  plus  vive 
lumiere  sur  le  mechanisme  des  fonctions  de  cette 
merveilleuse  puissance.” 

This  difficulty  appears  to  me  to  arise  from  #his 
having  regarded  respiration  as  a function  wholly 
depending  on  a combination  of  the  nervous  and 
muscular  powers ; whereas  it  seems  evident,  I 
think,  that  the  sensorial  power  also  shares  in  it. 
The  muscles  of  respiration  are,  in  the  strictest 
sense  of  the  word,  muscles  of  voluntary  motion ; 
we  can  at  pleasure  interrupt,  renew,  accelerate,  or 
retard  their  action  ; and,  if  we  cannot  wholly  pre- 
vent it,  it  is  for  the  same  reason  that  we  cannot 
prevent  the  action  of  the  muscles  of  the  arm,  when 
fire  is  applied  to  the  fingers.  The  sensation  occa- 
sioned by  the  interruption  of  a supply  of  air  to 
the  lungs  is  greater  than  can  be  voluntarily 
borne.  Respiration  continues  in  sleep  for  the 
same  reason  that  we  turn  ourselves  in  sleep  when 
our  posture  becomes  uneasy.  It  continues  in 
apoplexy  for  the  same  reason  that  the  patient  ge- 
nerally moves  his  limbs  if  they  are  violently  ir- 
ritated. If  [respiration  continues  in  apoplexy 


223 


when  no  irritation  of  the  limbs,  however  violent, 
excites  the  patient  to  move  them ; it  arises  from 
the  interruption  of  a supply  of  air  to  the  lungs 
producing  a greater  degree  of  irritation  than  any 
other  means  we  can  employ.  W e know  instances 
in  which  the  hand  has  been  voluntarily  held  in 
the  fire,  but  we  know  of  none  where  the  breath- 
ing has  been  voluntarily  discontinued  till  the  lungs 
were  injured.  As  the  insensibility  increases  in 
apoplexy,  the  breathing  becomes  less  frequent; 
and  when  the  former  becomes  such  that  no  means 
can  longer  excite  any  degree  of  feeling,  the 
breathing  ceases. 

By  a certain  sensation  a wish  is  excited  to  ex- 
pand the  chest.  This  is  an  act  of  the  sensorium. 
Till  this  act  take  place,  the  nervous,  as  well  as 
the  muscular  power,  by  which  its  expansion  is 
effected  is  inert,  it  is  in  vain  that  these  powers  re- 
main, if  the  power  which  calls  them  into  action 
be  lost.  Thus  the  removal  of  the  brain  puts  a 
stop  to  respiration. 

It  is  said  that  the  motions  of  inspiration  must 
be  involuntary,  because  we  are  in  general  un- 
conscious of  them  ? But  do  we  not  become  more 
or  less  so  of  all  habitual  acts  of  volition?  We 
frequently  hear  such  observations  as  the  fol- 
lowing ; if  I did  so,  I did  it  unconsciously.  Stop 
a person  who  is  walking,  he  cannot  tell  which 
leg  he  last  moved ; stop  a person  who  is  playing 
on  an  instrument,  he  cannot  tell  which  fingers  he 


last  employed ; yet  all  such  acts  are  strictly  acts 
of  volition.  If  we  are  reminded  of  them  we  can 
always  interrupt,  renew,  retard  or  accelerate  them 
at  pleasure.  We  have  no  difficulty  in  perceiving 
and  changing  in  any  way  we  please  the  motions 
of  respiration,  when  we  choose  to  attend  to  them ; 
but  as  there  is  no  other  act  of  volition  so  habitual, 
there  is  none  so  apt  to  escape  our  attention. 

The  above  explanation  of  the  manner  in  which 
the  removal  of  the  brain  puts  a stop  to  respiration 
will  be  readily  admitted,  I think,  when  we  con- 
sider to  what  part  of  the  brain  impressions  from 
the  lungs  are  conveyed.  It  is  evidently  to  the 
part  where  the  eighth  pair  of  nerves,  which  sup- 
plies them,  joins  that  part  of  the  brain  from  which 
the  spinal  marrow  originates.  Now  it  appears 
from  the  experiments  in  which  M.  le  Gallois  re- 
moved the  brain  by  slices,  that  respiration  con- 
tinued till  he  removed  the  part  of  the  medulla  ob- 
longata in  which  those  nerves  originate,  and  then 
instantly  ceased.  In  these  experiments,  how- 
ever, the  power  of  the  muscles  of  inspiration  and 
the  nervous  power  which  excites  them  still  re- 
main, as  may  be  easily  ascertained  by  stimuli 
properly  applied  to  the  spinal  marrow.  It  is  the 
influence  of  the  sensorial  power  which  is  lost. 

We  cannot,  perhaps,  have  a better  instance  of 
the  distinct  operation  of  the  sensorial,  nervous 
and  muscular  powers,  than  in  the  case  before  us, 
although  they  all  here  conduce  to  the  same  end. 


22o 


We  may  destroy  any  one  of  them  and  leave  the 
others  unimpaired.  The  destruction  of  the  sen- 
sation by  which  we  will  to  inspire,  we  have  just 
seen,  does  not  destroy  the  nervous  or  muscular 
power  employed  in  inspiration.  By  means  ap- 
plied to  the  muscles  of  inspiration  we  may  de- 
stroy their  mechanism  without  depriving  any  part 
of  the  spinal  marrow  of  its  power,  or  at  all  im- 
pairing the  above  sensation : and  we  may  destroy 
the  nervous  influence  which  excites  these  mus- 
cles by  destroying  a certain  part  of  the  spinal 
marrow,  while  they,  as  may  be  ascertained  by 
the  application  of  stimuli,  perfectly  retain  their 
vigour,  and  the  sensation  which  excites  the  wish 
to  inspire,  though  as  in  the  last  case,  useless,  re- 
mains unimpaired : nay,  if  any  two  of  these  pow- 
ers be  destroyed,  they  leave  the  remaining  power 
unimpaired.  The  destruction  of  the  muscles  ' of 
inspiration,  and  of  the  nervous  influence  which 
excites  them,  does  not  destroy  the  sensation  by 
which  we  will  to  inspire ; nor  does  the  destruc- 
tion of  this  sensation  and  the  nervous  influence 
at  all  impair  the  power  of  the  muscles  ; and  we 
may  destroy  the  sensation  in  question,  and  the 
power  of  the  muscles,  without  impairing  the  ner- 
vous influence  which  excites  them.  So  far  from 
true  is  the  position  of  M.  le  Gallois,  that  the  pow- 
er on  which  all  the  motions  of  inspiration  depend, 
resides  in  the  medulla  oblongata. 

Much  has  been  written  by  Whytt  and  many 
81 


226 


other  physiologists,  respecting  the  cause  of  the 
first  inspiration.  I cannot  help  thinking  that  the 
difficulty  vanishes,  when  we  regard  the  muscles 
of  inspiration  as  merely  muscles  of  voluntary 
motion.  The  young  animal  throws  them  into 
action  to  remove  a painful  sensation  occasioned 
by  the  want  of  that  change  in  the  blood,  which 
is  produced  by  the  influence  of  the  air  in  the 
lungs ; a process  necessary  to  the  existence  of 
the  animal  as  soon  as  its  connection  with  the 
mother  ceases,  and  which  can  only  be  effected 
by  expanding  the  chest,  and  thus  receiving  air 
into  the  lungs.  It  seems  to  be  expanded  for  the 
first  time  precisely  for  the  same  reason  that  the 
foetus  changes  its  position  for  the  first  time  by 
acting  with  the  muscles  of  the  trunk  and  limbs. 
In  both  cases  he  endeavours  to  remove  an  uneasy 
sensation,  and  nature  has  given  him  the  power 
to  remove  it  by  calling  into  action  certain  mus- 
cles subjected  to  the  will.  The  first  act  of  de- 
glutition, if  it  does  not  occur  in  the  foetal  state, 
appears  to  be  an  act  of  precisely*the  same  nature 
with  the  first  inspiration.  In  both  cases,  a cer- 
tain set  of  muscles  of  voluntary  motion  is  thrown 
into  action  to  satisfy  a craving,  which  had  no 
existence  in  that  state.* 

* It  may  be  objected  to  this  view  of  the  first  inspiration, 
that  the  animal  often  breathes  before  a ligature  is  thrown 
round  the  umbilical  chord:  but  we  have  no  reason  to  believe, 
that  the  secondary  change,  effected  in  the  blood  of  the  foetus 


227 


When  respiration  ceases,  most  of  the  pulmo- 
nary vessels  and  left  side  of  the  heart  are  no 
longer  supplied  with  their  proper  stimulus ; and 
feel  more  directly  perhaps  the  debilitating  influ- 
ence of  black  blood.  Their  functions,  therefore,, 
begin  to  fail.  In  proportion  as  this  happens,  the 
blood  accumulates  in  the  lungs,  and  the  right 
side  of  the  heart  experiences  an  increased  dif- 
ficulty in  emptying  itself.  By  the  operation  of 
these  causes,  both  sides  of  the  heart,  in  warm 
blooded  animals,  soon  lose  their  power  after  re- 
spiration ceases.  The  arteries,  under  such  cir- 
cumstances, it  is  evident,  cannot  long  supply 
fluids  proper  for  the  purposes  of  secretion,  the 
nervous  and  muscular  solids,  therefore,  soon  de- 
viate from  the  state  necessary  for  the  functions 
of  life,  which  at  length  cease  in  every  part. 

The  above  appears  to  be  the  order  in  which 
the  functions  always  cease  in  death,  whether  it 
be  occasioned  by  injury  of  the  sanguiferous,  or 
nervous  systems,  or  both,  with  the  exception  of 

by  the  vicinity  of  the  maternal  blood  of  the  placenta,  although 
this  gives  it  the  florid  colour,  as  may  be  seen  by  opening  the 
vessels*  of  the  chord,  is  sufficient  for  the  functions  of  the  per- 
fect animal.  One  of  these  functions,  which  we  have  reason 
to  believe  from  many  phenomena,  as  well  as  from  direct  ex- 
periments, is  intimately  connected  with  the  change  effected 
on  the  blood  by  the  air,  the  evolution  of  caloric,  it  is  evident, 
is  immediately  after  birth  required  to  be  in  a state  of  much 
greater  activity  than  in  the  foetus,  which  is  surrounded  by  a 
medium  of  its  own  temperature. 


228 


those  cases  in  which  the  nervous  system  is  so 
impressed,  as  immediately  to  destroy  all  the  func- 
tions. The  degree  of  vital  energy  required  for 
the  sensorial,  appears  to  be  greater  than  that 
required  for  the  nervous  and  muscular  functions, 
the  sensorial  functions  always,  except  in  the  case 
just  mentioned,  in  which  death  is  instantaneous 
throughout  the  system,  ceasing  first.  Respiration, 
consequently,  is  the  first  vital  function  which 
fails,  being  the  only  one  to  which  the  sensorial 
power  is  necessary. 

Bichat  has  been  at  great  pains  to  ascertain  the 
effects  of  black  blood  on  the  lungs  and  other  or- 
gans. To  his  experiments  on  this  subject  I re- 
fer the  reader.  There  are  but  few  parts  of  the 
physiological  works  of  Bichat  which  can  be  con- 
fidently referred  to.  In  general  he  has  allowed 
his  reasonings  to  go  far  beyond  the  evidence  af- 
forded by  his  observations  and  experiments.  1 
shall  take  this  opportunity  of  making  a few  re- 
marks relating  to  the  principal  points  in  which  I 
have  differed  from  him.  He  was  unacquainted 
with  the  fact,  that  the  spinal  marrow  performs  its 
functions  independently  of  the  brain,*  and  there - 

* The  independence  of  the  spinal  marrow  on  the  brain, 
as  far  as  relates  to  its  power  over  the  muscles  of  voluntary 
motion,  appears  from  the  experiments  of  M.  le  Gallois  ; and 
as  far  as  relates  to  secretion,  from  experiments  laid  before 
the  reader  in  the  second  section  of  the  seventh  chapter  of 
this  Inquiry. 


229 


tore  did  not  see  the  difficulty  respecting  respira- 
tion stated  by  M.  le  Gallois,  but  seems  to  think 
that  the  division  of  the  spinal  marrow  near  the 
head,  occasions  death  by  preventing  the  nervous 
influence  of  the  brain  from  reaching  the  intercos- 
tal muscles  and  diaphragm.  The  want  of  this 
knowledge  leads  him  into  inaccuracies,  both  in 
his  observations  on  death  and  other  passages; 
which  are  increased  by  his  not  being  aware,  that 
the  sensorial  and  nervous  powers  have  no  direct 
dependence  on  each  other.*  He  is  led  into 
more  obvious  errors,  as  far  as  I am  capable  of 
judging,  in  various  parts  of  his  works,  particular- 
ly in  those  which  relate  to  the  passions  and  the 
death  of  the  brain,  by  his  not  knowing  that  the 
heart  and  blood  vessels  may  be  directly  influ- 
enced, and  even  their  power  directly  destroyed, 
by  agents  acting  either  on  the  brain  or  spinal 
marrow  ; and  by  his  supposing  that  the  ganglions 
are  capable  of  preparing  nervous  influence  inde- 
pendently of  the  brain  and  spinal  marrow,  a sup- 
position which  we  have  seen  contradicted  by  many 
experiments,  and  which  Bichat  does  not  attempt 
to  support  by  any  observation  or  experiment  di- 
rectly bearing  on  the  point. 

* It  appears,  however,  from  various  facts,  as  I have  alrea- 
dy had  occasion  to  observe,  that  neither  of  these  classes  of 
functions  is  confined  either  to  the  brain  or  spinal  marrow ; 
both  organs  partaking  of  both,  although  the  brain  is  the  chief 
seat  of  the  sensorial,  and  the  spinal  marrow,  of  the  nervous 
functions. 


‘ 230 

These  circumstances  have  even  led  him  into 
the  most  striking  inconsistencies  in  his  great  di- 
vision of  the  functions  into  organic  and  animal. 
If  the  experiments  which  have  been  laid  before 
the  reader  be  correct,  the  sensorial  functions  con- 
stitute the  animal,  and  the  nervous  and  muscular, 
the  organic  life.  To  this,  it  may  be  objected, 
that  plants  and  the  less  perfect  animals  have  no 
nervous  system.  Would  it  not  be  more  correct 
to  say,  that  the  operation  of  their  nervous  system 
is  more  confined?  Wherever  secretion  is  per- 
formed, the  nervous  influence,  or  a power  resem- 
bling it,  must  exist.  In  order  that  a being  pos- 
sessed of  the  nervous  and  muscular  systems  alone, 
may  live  in  perfect  vigour,  it  is  only  necessary, 
provided  it  be  supplied  with  food,  that  respiration 
should  be  performed  as  circulation  is,  by  powers 
of  involuntary  motion.  A being  so  formed, 
thougli  possessed  of  all  the  powers  of  life,  M ould 
be  wholly  unconnected  w-itli  the  external  world, 
except  by  deriving  its  food  and  the  influence  of 
the  air  from  it ; all  other  intercourse  with  that 
world  depending  on  the  sensorial  pow  er.  Such 
is  the  life  of  vegetables,  and  w e have  reason  to 
believe,  that  that  of  the  lowest  class  of  animals 
differs  from  it  in  little  else  than  degree.*  An 

* I do  not  mean  to  say  that  the  change  effected  on  the 
air  by  plants  is  of  the  same  nature  with  that  effected  by  ani- 
mals, or  that  they  possess  a circulation  similar  to  that  of 


231 


animal  of  this  class  approaches  as  nearly,  as 
facts  will  allow  us  to  suppose,  to  one  possessing 
merely  organic  life,  according  to  Bichat’s  defini- 
tion of  it ; yet,  in  the  second  section  of  his  sixth 
article,  he  maintains,  that  every  thing  relative  to 
the  passions  belongs  to  the  organic  life ; an  incon- 
sistency which  alone  is  sufficient  to  prove  a radi- 
cal defect  in  his  system.  Can  the  passions  belong 
alone  to  that  life  in  which  they  never  can  be  ex- 
cited, in  which  they  never  can  operate!  Even 
according  to  Bichat’s  definition  of  organic  life,  it 
is  common  to  the  animal  and  vegetable  world. 

No  writer,  as  far  as  I know,  has  attempted  to 
explain  the  following  difficulty  respecting  the 
foetal  state.  The  influence  of  the  brain  and  spi- 
nal marrow,  we  have  seen,  is  necessary  to  the 
function  of  secretion,  and  consequently  to  the  life 
and  growth  of  the  body  ; but  foetuses  have  been 
born  alive  without  either  of  these  organs  * To 
remove  this  part  of  the  difficulty  it  has  been  said 
that  in  such  foetuses  the  nerves  perform  the  func- 
tions of  the  brain  and  spinal  marrow.  This  is 
not  only  a gratuitous  supposition,  but  opposed 
by  almost  every  fact  on  the  subject  relating  to  the 

animals  ; but  we  know  that  air  is  necessary  to  their  exist- 
ence, that  some  change  in  it  is  effected  by  them,  and  that  in 
their  vessels  or  canals  there  is  a continual  motion  of  their 
fluids. 

* Page  6 k 


232 


perfect  animal.  If,  however,  we  admit  this  sup- 
position, it  will  go  but  a very  short  way  towards 
removing  the  difficulty.  How  shall  we  account 
for  the  life  and  growth  of  the  foetus,  when  the 
whole  nervous  system  appears  an  inorganised  sub- 
stance, and,  as  far  as  we  can  see,  wholly  incapa- 
ble of  its  functions  ; while  the  sanguiferous  sys- 
tem appears  to  be  completely  organised,  and  ca- 
pable of  all  its  functions?  Nay,  the  heart  may 
be  seen  performing  its  functions  in  the  chick  in 
ovo  when  no  vestige  of  brain  or  spinal  marrow 
can  be  traced.  What  in  all  these  cases  supplies 
the  place  of  nervous  influence  ? What  influence 
co-operates  with  the  sanguiferous  system  in  ef- 
fecting the  secretions  ? Did  the  evolution  of  the 
brain  and  spinal  marrow  in  the  formation  of  the 
animal  keep  pace  with  that  of  the  sanguiferous 
system,  a difficulty  of  some  weight  would  still 
remain.  If  the  sanguiferous  and  nervous  sys- 
tems be  co-existent,  the  formation  of  the  animal 
must  begin  at  more  than  one  point,  a supposition 
contrary  to  the  simplicity  observed  in  the  opera- 
tions of  nature. 

The  experiments  which  have  been  laid  before 
the  reader  do  not  explain  these  difficulties ; but 
they  suggest  an  explanation  of  them,  the  accura- 
cy of  which  must  be  ascertained  by  further  expe- 
riments. If  the  nervous  influence  be  galvanism, 
there  may  be  some  apparatus  in  the  uterine  sys- 
tem for  collecting  and  applying  this  agent,  which 


238 


is  every  where  diffused,  till  the  brain  and  spinal 
marrow  can  perform  their  functions,  and  which 
may  continue  to  supply  their  place  where  they  ne- 
ver exist.  We  have  seen  that  galvanism  is  ca- 
pable of  performing  all  the  functions  of  the  ner- 
vous system,  properly  so  called.  In  combination 
with  the  powers  of  circulation  it  can,  therefore, 
perform  all  the  functions  essential  to  the  life  of 
the  perfect  animal  except  respiration,  to  which, 
we  have  seen  the  sensorial  power  is  necessary.  It 
is  worthy  of  remark,  that  this  is  the  only  function, 
immediately  essential  to  life  in  the  perfect  ani- 
mal, which  does  not  exist  in  the  foetal  state. 

We  have  seen  that  in  dying  the  sensorial  pow- 
ers are  the  first  which  cease,  their  continuance 
seeming  to  require  the  most  perfect  co-operation 
of  the  sanguiferous  and  nervous  powers.  For  the 
same  reason  they  appear  to  he  the  last  which  are 
formed. 

If  the  foregoing  view  of  the  subject  should,  on 
investigation,  be  found  correct,  we  must  regard 
the  rudiment  of  life  as  confined  to  the  central  part 
of  the  circulation,  from  which,  by  the  power  of 
galvanism,  collected  by  some  means  external  to 
the  foetus,  all  other  parts  are  gradually  evolved, 
till  within  the  foetus  itself  a galvanic  apparatus 
of  sufficient  power  for  the  performance  of  the  ner- 
vous functions  is  produced;  the  sensorial  func- 
tions appearing  to  be  superadded  when  all  the 
others  approach  to  their  perfect  state. 

A difficulty  similar  to  that  we  have  been  consi- 
32 


234 


deriug,  exists  respecting  the  lowest  class  of  ani- 
mals in  which  no  nervous  system  can  be  disco- 
vered, and  vegetables.  Both  of  these  classes  of 
beings  must  necessarily  possess  the  secreting 
power.  It  is  requisite  to  the  formation  and  growth 
of  their  bodies ; and  Mr.  Hunter  found  that  the 
most  imperfect  animals  are  capable  of  occasioning 
an  evolution  of  caloric.  Is  it  probable  that,  in  a 
more  advanced  state  of  knowledge,  we  shall  find 
in  these  beings  means  of  collecting  and  applying 
galvanism  ? 


CHAP.  XI. 

A review  of  the  inferences  from  the  preceding 
experiments  and  observations. 

From  the  various  experiments  and  observa- 
tions which  have  been  laid  before  the  reader  it 
appears, 

1.  That  the  vessels  of  circulation  possess  a 
power  capable  of  supporting  a certain  motion  of 
the  blood  independently  of  the  heart.  Exp.  24, 
75,  76- 

2.  That  the  power  both  of  the  heart  and  ves- 
sels of  circulation  is  independent  of  the  brain  and 
spinal  marrow.  Exp.  1,  2,  3,  4, 5,  6,  7,  8,  9,  10, 
11,  12, 13. 

3.  That  the  nervous  influence  is  capable  of  act- 


235 


ing  as  a stimulus  both  to  the  heart  and  vessels  of 
circulation.  Exp.  1 4,  15,1 6, 17,  18,  23,  26,  27, 
28. 

4.  That  the  nervous  influence  is  capable  of 
acting  as  a sedative  both  to  the  heart  and  vessels 
of  circulation,  even  to  such  a degree  as  to  destroy 
their  power.  Exp.  16, 17, 18, 19,  20,  21,  22,  26, 
27,  28,  29,  30. 

5.  That  the  effect  of  the  sedative  is  not  the  re- 
sult of  the  excess  of  stimulus,  but,  like  excitement, 
the  direct  operation  of  the  agent.  See  the  obser- 
vations after  Exp.  40,  and  the  experiments  there 
referred  to.* 

6.  That  the  power  of  the  muscles  of  voluntary 
motion  is  independent  of  the  nervous  system,  and 
that  their  relation  to  this  system  is  of  the  same 
nature  with  that  of  the  heart  and  vessels  of  circu- 
lation, the  nervous  power  influencing  them  in  no 
other  way  than  other  stimuli  and  sedatives  do. 
Exp.  31,  32,  and  the  observations  under  Exp.  32. 

7-  That  the  cause  of  the  muscles  of  voluntary 
and  involuntary  motion  appearing  at  first  view 
essentially  to  differ  in  their  nature,  is  their  being 
excited  by  stimuli  essentially  different,  the  former 
being  always  excited  by  the  nervous  influence, 

* A moderate  application  of  every  agent  appears  to  act 
as  a stimulus  •,  an  excessive  application  of  it,  as  a sedative. 
The  quantities  which  act  as  stimulus  and  sedative  bear  no 
particular  proportion  to  each  other,  but  in  different  agents 
exist  in  every  possible  proportion. 


236 


the  latter  though  occasionally  excited  by  this  in- 
fluence in  all  their  usual  functions  obeying  other 
stimuli.  See  the  observations  under  Exp.  32. 

8.  That  the  brain,  and  spinal  marrow  act  each 
of  them,  directly  on  the  heart  as  well  as  on  the 
muscles  of  voluntary  motion.  Exp.  18,  19,  23. 

9.  That  the  laws  which  regulate  the  effects  of 
stimuli  applied  to  the  brain  and  spinal  marrow 
on  the  heart  and  muscles  of  voluntary  motion  are 
different.  Exp.  33,  34,  35,  36,  37,  38,  39,  40. 

10.  That  mechanical  stimuli  applied  to  the 
brain  and  spinal  marrow  are  better  fitted  to  ex- 
cite the  muscles  of  voluntary  motion,  and  che- 
mical stimuli,  the  heart.  Exp.  33,  34,  35,  36, 
37,  38. 

11.  That  neither  mechanical  nor  chemical  sti- 
muli applied  to  the  brain  and  spinal  marrow  ex- 
cite the  muscles  of  voluntary  motion,  unless  they 
are  applied  near  to  the  origin  of  their  nerves,  and 
consequently  that  these  muscles  are  excited  by 
stimuli  applied  to  very  minute  parts  of  the  above 
organs.  Exp.  33,  35,  37- 

12.  That  both  mechanical  and  chemical  sti- 
muli applied  to  any  considerable  part  of  the  brain 
or  spinal  marrow  increase  the  action  of  the  heart, 
which  cannot  be  increased  by  any  stimulus  ap- 
plied to  a minute  part  of  these  organs.  Exp.  34, 
36,  38,  41, 42,  43. 

13.  That  the  heart  obeys  a much  less  power- 


237 


fal  stimulus  applied  to  the  brain  and  spinal  mar- 
row than  the  muscles  of  voluntary  motion  do. 
Exp.  35,  36,  37,  &c.  and  observations  after 
Exp.  43. 

14.  That  stimuli  applied  to  the  brain  and  spi- 
nal marrow  excite  irregular  action  in  the  muscles 
of  voluntary  motion.  Exp.  38,  35.,  37- 

15.  That  no  stimulus  applied  to  the  brain  or 
spinal  marrow  excites  irregular  action  in  the 
heart  or  vessels  of  circulation,  nor  is  their  ac- 
tion rendered  irregular  by  sedatives,  unless  a 
blow,  which  crushes  a considerable  part  of  the 
brain  or  spinal  marrow,  be  regarded  as  a seda- 
tive. Exp.  28,  39,  &c. 

16.  That  the  excitement  of  the  muscles  of  vo- 
luntary motion  takes  place  chiefly  at  the  moment 
at  which  the  stimulus  is  applied  to  the  brain  and 
spinal  marrow,  while  that  of  the  heart  may  ge- 
nerally be  perceived  as  long  as  the  stimulus  is 
applied.  Exp.  40. 

17.  That  after  all  stimuli  applied  to  the  brain 
and  spinal  marrow  fail  to  excite  the  muscles  of 
voluntary  motion,  both  mechanical  and  chemical 
stimuli  so  applied  still  excite  the  heart.  Exp.  38. 

18.  That  all  the  foregoing  differences  in  the 
effects  of  stimuli  applied  to  the  brain  and  spinal 
marrow  on  the  heart  and  muscles  of  voluntary  mo- 
tion are  referable  to  the  following  law : That  the 
heart  is  excited  by  all  stimuli  applied  to  any  con- 


238 


siderable  part  of  the  brain  or  spinal  marrow, 
while  the  muscles  of  voluntary  motion  are  only 
excited  by  intense  stimuli  applied  to  certain  small 
parts  of  these  organs.  See  the  observations  un- 
der Exp.  43. 

19.  That  the  function  of  secretion  is  destroyed 
by  dividing  the  nerves  of  the  secreting  organs. 
Exp.  44,  45. 

20.  That  it  may  be  restored  after  it  is  thus 
destroyed  by  the  galvanic  influence.  Exp.  46,  47,, 
48,  49. 

21.  That  lessening  the  extent  of  the  nervous 
system  by  destroying  the  influence  of  any  consi- 
derable part  either  of  the  brain  or  spinal  marrow, 
deranges  the  secreting  power. . Exp.  58,  59,  60, 
61,  62. 

22.  That  dividing  the  spinal  marrow  does  not 
derange  the  secreting  power.  Exp.  63. 

23.  That  the  vessels  of  secretion  only  convey 
the  fluids  to  be  operated  upon  by  the  nervous  in- 
fluence. See  Chap.  5.  Sec.  3,  and  the  experi- 
ments there  referred  to. 

24.  That  these  vessels,  like  the  vessels  of  cir- 
culation, are  independent  of,  but  influenced  by, 
the  nervous  system.  Ib. 

25.  That  the  peristaltic  motion  of  the  stomach 
and  intestines  is  independent  of  the  nervous  sys- 
tem. Exp.  50,  51. 


239 


26.  That  it  is  capable  of  being  influenced 
through  it.  See  the  beginning  of  Chap.  7- 

27.  That  in  the  stomach  of  the  rabbit,  and  pro- 
bably in  that  of  similar  animals,  the  food  when 
received  into  the  stomach  remains  at  rest  in  the 
central  part  of  this  organ,  and  unmixed  with  the 
food  previously  taken ; and  that  it  is  changed  in 
proportion  as  it  approaches  the  surface  of  the  sto- 
mach, in  consequence  of  that,  previously  there, 
being  moved  on  towards  the  pylorus.  Exp.  53, 
54,  56. 

28.  That  the  food  is  most  mixed  with  the  fluids 
of  the  stomach,  and  the  greatest  change  is  effected 
in  it  in  the  cardiac  end  of  the  stomach.  Exp.  56. 

29.  That  the  food  is  much  dryer  and  of  a more 
uniform  consistence,  its  digestion  being  further 
advanced,  in  the  pyloric  than  in  the  cardiac  end 
of  the  stomach.  See  Exp.  55,  and  the  observa- 
tions under  it. 

30.  That  the  efforts  to  vomit  occasioned  by  the 
division  of  the  eighth  pair  of  nerves,  arise  from 
fresh  food  coming  into  contact  with  the  surface  of 
the  stomach,  no  longer  covered  with  its  proper 
fluids.  See  the  observations  near  the  end  of  the 
first  Section  of  Chap.  7«  and  the  experiments  there 
referred  to. 

31.  That  the  muscular  power  of  the  stomach 
remains  after  the  division  of  the  eighth  pair  of 
nerves,  by  which  all  that  part  of  the  food  which 
has  undergone  the  action  of  the  gastric  juice  is 


carried  into  the  intestine,  undigested  food  alone 
remaining  in  the  stomach.  Ib. 

32.  That  the  secreting  power  of  the  stomach 
is  almost  as  much  deranged  by  destroying  a con- 
siderable part  of  the  spinal  marrow,  as  by  divid- 
ing the  eighth  pair  of  nerves.  Exp.  58,  59,  60. 

33.  That  a similar  observation  applies  to  the 
secreting  power  of  the  lungs.  Exp.  44,  4:5,  4:9. 

34.  That  the  stomach  and  lungs,  like  the  san- 
guiferous system,  are  influenced  by  every  part  of 
the  brain  and  spinal  marrow.  Exp.  44,  45,  58, 
59,  60,  61,  62. 

35.  That  the  destruction  of  any  considerable 
part  of  the  spinal  marrow  lessens  the  tempera- 
ture of  the  animal.  Exp.  58,  59,  60. 

36.  That  the  galvanic  influence  occasions  an 
evolution  of  caloric  from  arterial  blood,  if  it  be 
subjected  to  this  influence  as  soon  as  it  leaves  the 
vessels.  Exp.  64,  65,  66,  67. 

37.  That  the  galvauic  influence  occasions  no 
evolution  of  caloric  from  venous  blood,  although 
subjected  to  it  as  soon  as  the  blood  leaves  the  ves- 
sels. Exp.  68,  69,  70. 

38.  That  there  is  no  evolution  of  gaseous  fluid 
from  arterial  blood  on  its  leaviug  the  vessels. 
Exp.  71. 

39.  That,  if  caloric  be  admitted  to  be  a sub- 
stance, its  evolution  from  the  blood  being  effect- 
ed by  the  same  means  by  which  the  secreted  fluids 


241 


are  formed,  it  must  be  regarded  as  a secretion. 
See  the  observations  under  Exp.  70,  and  page 
228. 

40.  That  the  division  of  the  spinal  marrow 
does  not  destroy  any  of  the  functions  of  either  half 
of  it,  (22)  the  paralysis  of  the  lower  part  of  the 
body,  occasioned  by  its  division,  arising  from  that 
part  having  its  communication  with  the  principal 
source  of  sensorial  power  destroyed.  See  Exp. 
63,  and  the  observations  on  the  sensorial  power 
in  Chap.  10. 

41.  That  the  ganglions  are  a secondary  cen- 
tre of  nervous  influence,  whose  nerves  are  as  ex- 
tensively distributed  as  those  which  proceed  from 
the  brain  and  spinal  marrow.  See  Chap.  9. 

42.  That  the  ganglions  are  the  means  by  which 
the  influence  of  every  part  of  the  brain  and  spinal 
marrow  is  bestowed  on  the  parts,  which  we  have 
found  influenced  by  every  part  of  these  organs. 
See  Chap.  9,  and  the  experiments  there  refer- 
red to. 

43.  That  the  influence  of  every  part  of  the 
brain  and  spinal  marrow  is  bestowed  on  all  parts 
directly  or  indirectly  necessary  to  the  due  per- 
formance of  secretion,  this  function  requiring  the 
influence  of  every  part  of  these  organs  (21).  Exp. 
44, 45,  58,  59,  60,  61,  62. 

44.  That  the  position  of  the  ganglions  and 

33 


242 

the  distribution  of  their  nerves  tend  to  confirm  th& 
view  of  their  use  afforded  by  the  above  experi- 
ments. See  Chap.  9. 

45.  That  we  have  reason  to  believe,  that  the 
great  sympathetic  nerve  arises  from  the  spinal 
marrow.*  Ibid. 

46.  That  the  proof  of  the  vessels  possessing  a 
principle  of  motion  independent  of  their  elasticity, 
which  bears  the  same  relation  to  the  nervous  sys- 
tem with  the  excitability  of  the  heart ; not  only  as 
far  as  respects  the  kind  of  influence  which  they 
derive  from  that  system,  (43)  and  the  way  in 

* This  position  does  not  rest  as  M.  le  Gallois  maintains  on 
the  fact,  that  crushing  any  considerable  part  of  the  spinal 
marrow  destroys  the  power  of  the  heart,  while  the  removal 
of  the  brain  leaves  it  unimpaired,  because  the  leader  has 
seen  that  crushing  the  brain  in  like  manner  destroys  the 
power  of  the  heart,  which  remains  uninfluenced  by  the  re- 
moval of  the  spinal  marrow. 

It  appears  to  rest  on  the  following  circumstances.  The 
sympathetic  nerve  is  largest  about  the  middle  of  the  spine, 
becoming  less  as  it  ascends  and  descends.  We  have  found 
from  direct  experiment  that  the  thoracic  and  abdominal  vis- 
cera are  influenced  by  every  part  of  the  spinal  marrow,  which 
can  only  be  through  the  medium  of  this  nerve,  the  influence 
of  the  brain  on  the  other  hand,  as  appears  also  from  direct 
experiment,  being  conveyed  to  these  viscera  by  the  eighth 
pair  of  nerves.  Bichat  found  that  the  effects  of  dividing  the 
eighth  pair  of  nerves  in  the  neck  are  not  increased  by  divid- 
ing in  the  same  place  the  great  sympathetic  nerve.  See 
Chap.  9. 


243 


which  it  is  supplied  to  them,  (42)  but  also  as  far 
as  respects  the  purposes  for  which  it  seems  to  be 
bestowed  on  them,  (43)  affords  a strong  argument 
for  believing,  that  this  power  is  of  the  same  nature 
with  that  of  the  heart.  See  the  Experiments  re- 
lated in  the  two  first  Chapters  of  the  present  part 
of  this  Inquiry,  also  Exp.  39,  44,  45,  58,  59,  60, 
61,  62,  and  Chap.  5,  Sec.  3,  and  Chap.  9. 

47-  That  the  various  functions  of  the  animal 
body  may  be  divided  into  sensorial,  nervous,  and 
muscular.  See  Chap.  10,  and  the  experiments 
there  referred  to. 

48.  That  the  sensorial  power  is  not  wholly 
confined  to  the  brain,  nor  the  nervous  to  the  spi- 
nal marrow,  both  powers  in  a greater  or  less  de- 
gree residing  in  both  organs.  See  Exp.  72,  and 
the  observations  which  precede  and  follow  it. 

49.  That  the  division  of  the  brain  into  cere- 
brum and  cerebellum  seems  to  relate  to  the  senso- 
rial functions,  since  the  muscles  both  of  voluntary 
and  involuntary  motion  appear  to  bear  the  same 
relation  to  both.  Exp.  33,  34,  35,  36. 

50.  That  what  we  call  death  is  the  ceasing  of 
the  sensorial  power  alone,  the  nervous  and  mus- 
cular powers  still  continuing.  Exp.  73,  74,  7&t 
76,  77?  78,  79,  80,  81,  82,  83,  and  the  observa- 
tions preceding  and  following  these  experiments.  ’ 

51.  That  in  the  function  of  respiration  the  sen- 
sorial, nervous,  and  muscular  powers  are  com- 


bined.  See  the  observations  after  Exp.  83,  and 
the  experiments  there  referred  to. 

52.  That  it  is  owing  to  the  ceasing  of  respira- 
tion, that  the  destruction  of  the  sensorial  power 
is  followed  by  that  of  the  nervous  and  muscular 
powers.  Ibid. 

53.  That  whatever  be  the  cause  of  death  the 
functions  cease  in  this  order,  unless  the  sensorial 
or  nervous  system  be  so  impressed  as  instantly  to 
destroy  all  the  functions.  Ibid. 

Such  are  the  immediate  inferences  from  the  ex- 
periments and  observations  which  have  been  laid 
before  the  reader.  By  comparing  them  together 
we  arrive  at  the  following  conclusions. 

The  power  of  the  muscles  both  of  voluntary 
and  involuntary  motion  is  independent  of  the  ner- 
vous system,  and  arises  from  the  mechanism  of 
the  muscular  fibre  itself.  Both  these  sets  of 
muscles  are  equally  capable  of  being  excited  by 
the  nervous  influence,  but  while  this  influence  is 
the  sole  stimulus  to  which  the  muscles  of  volun- 
tary motion  are  subjected,  it  acts  only  occasionally 
on  the  muscles  of  involuntary  motion,  which  are 
excited  in  all  their  usual  actions  by  stimuli  inde- 
pendent of  it,  and  consequently  of  the  will. 
When  the  latter  muscles  are  excited  by  the  ner- 
vous influence,  it  is  not  applied  to  them  in  the 
same  way  as  to  the  muscles  of  voluntary  motion, 
to  which  it  is  sent  directly  from  the  brain  and  spi- 


245 


nal  marrow,  each  muscle  receiving  its  nervous  in- 
fluence from  a particular  part  of  these  organs ; 
while  to  the  muscles  of  involuntary  motion,  it  is 
sent  through  the  great  chain  of  ganglions,  each 
muscle  receiving  its  nervous  influence  from  every 
part  of  the  brain  and  spinal  marrow. 

The  excitement  of  the  muscles  of  involuntary 
motion  in  all  their  usual  functions,  appears  to  be 
rendered  independent  of  the  nervous  influence, 
because  these  functions  require  a more  uniform 
excitement  than  could  have  been  derived  from 
this  source ; and  they  appear  to  be  subjected  to 
the  influence  of  the  whole  brain  and  spinal  mar- 
row, because  they  are  directly  or  indirectly  sub- 
servient to  the  function  of  secretion,  which  re- 
quires for  its  due  performance  the  influence  of 
every  part  of  these  organs ; for  the  nervous  in- 
fluence is  not  supplied  by  the  brain  alone,  the  spi- 
nal marrow  supplying  a necessary  part  of  it,  and 
that  independently  of  any  operation  of  the  brain 
on  this  organ. 

In  the  function  of  secretion,  the  sanguiferous 
system  appears  ouly  to  supply  the  fluids  to  be 
operated  upon  by  the  nervous  influence ; and  the 
evolution  of  caloric,  which  supports  animal  tem- 
perature, is  also  effected  by  the  action  of  this  in- 
fluence on  the  blood. 

We  have  reason  to  believe  that  the  nervous 
influence  is  the  galvanic  fluid,  collected  by  the 


246 


brain  and  spinal  marrow,  and  sent  along  the 
nerves  ; galvanism  being,  not  only  of  all  artifi- 
cial means  of  exciting  the  muscles,  that  which 
seems  best  adapted  to  this  purpose,  but  capable 
of  boih  forming  the  secreted  fluids,  and  causing 
an  evolution  of  caloric  from  the  blood,  after  the 
nervous  influence  is  withdrawn.* 

The  nervous  power  is  not  more  distinct  from 
the  muscular,  than  it  is  from  the  sensorial  power. 
We  find  the  first  capable  of  its  functions  after 
the  last  is  withdrawn. 

The  only  function  essential  to  animal  life,  in 
which,  the  sensorial  power  is  concerned,  is  respi- 
ration, and  consequently  it  is  by  the  interruption 
of  this  function  that  the  removal  of  the  sensorial 
power  proves  fatal,  except  where  the  sensorium 
is  so  impressed  as  immediately  to  destroy  all  the 
functions. 

The  sensorial  power  appears  to  be  the  last 
which  is  produced,  and  the  first  whose  operation 

teases. 

* If  such  be  the  facts,  we  must  either  admit  the  identity  of 
the  nervous  influence  and  galvanism,  or  that  there  is  another 
power  capable  of  the  more  complicated  as  well  as  the  more 
simple  functions  of  the  nervous  influence,  an  inference  which 
is  surely  at  variance  with  all  just  rules  of  reasoning.  I have, 
in  various  parts  of  the  preceding  inquiry,  had  occasion  to 
mention  additional  arguments  in  favour  of  the  former  opi- 
nion, (see  Page  133,  141,  &c.)  and  in  the  next  chapter  the 
reader  will  find  some  facts  relating  to  the  human  body  itself 
tending  to  support  it. 


247 


The  foregoing  conclusions  seem  to  reconcile 
all  the  apparent  contradictions  stated  in  the  first 
part  of  this  inquiry. 

The  heart  continues  to  act  for  some  time  after  it 
is  removed  from  the  body,  and  performs  its  func- 
tions in  the  foetal  state  when  neither  the  brain  nor 
spinal  marrow  has  existed ; because  it  has  no 
direct  dependence  on  the  nervous  system,  and 
is  only  influenced  by  the  removal  of  the  brain 
and  spinal  marrow  in  the  perfect  animal,  in  con- 
sequence of  the  failure  of  respiration.* 

The  heart  is  supplied  with  nerves,  and  subject 
to  the  influence  of  the  passions,  because,  although 
independent  of  the  nervous  system,  it  is  capable 
of  being  influenced  through  it. 

Thus,  when  we  remove  the  brain  and  spinal 
marrow,  the  action  of  the  heart  is  unimpaired, 
because  it  is  independent  of  these  organs.  When 
we  crush  them,  it  is  enfeebled  or  destroyed,  be- 
cause it  is  influenced  through  them ; and  the 
greater  the  portion  destroyed,  and  the  more  sud- 
den its  destruction,  the  greater  injury  the  heart 

* It  is  evident  from  what  has  been  said,  that  could  we 
perfectly  imitate  the  function  of  respiration  after  the  removal 
of  the  brain  and  spinal  marrow,  the  heart  would  soon  begin  to 
feel  the  effects  of  the  general  failure  of  the  secreting  power ; 
the  failure  of  the  secreting  power  in  the  lungs,  indeed,  as  I 
have  already  had  occasion  to  observe,  probably  constitutes 
one  of  the  chief  differences  between  natural  and  artificial 
respiration. 


248 


Sustains.  These  facts  reconcile  the  apparent  con- 
tradictions in  the  experiments  of  M.  le  Gallo  is. 

The  heart  is  independent  of  the  will,  because  .it 
is  exposed  to  the  constantly  renewed  action  of  a 
stimulus,  over  which  the  will  has  no  control ; 
and  because  there  is  no  act  of  volition  which 
could  be  performed  through  the  medium  of  the 
heart. 

The  function  of  the  stomach  is  destroyed  by 
withdrawing  the  influence  of  the  brain  or  spinal 
marrow,  while  that  of  the  heart  is  unimpaired, 
because  the  function  of  the  heart  depends  wholly 
on  the  muscular  power,  which  we  have  found  in 
every  part  of  the  body  independent  of  the  nervous 
influence,  while  the  function  of  the  stomach  chiefly 
depends  on  the  secreting  power,  which  we  have 
found  every  where  dependent  on  this  influence. 
As  far  as  the  function  of  the  stomach  is  muscular, 
it  also  continues  after  the  nervous  influence  is 
withdrawn.  The  digested  part  of  the  food  is  still 
carried  onwards  into  the  intestine. 

The  difficulties  stated  by  M.  le  Gallois  re- 
specting the  function  of  respiration,  seem  to  dis- 
appear when  it  is  admitted,  that  although  the 
muscular  and  nervous  powers,  concerned  in  this 
function,  are,  as  M.  le  Gallois  states  them  to  be, 
independent  of  the  brain,  the  sensorial  power  is 
here  necessary  to  call  them  into  action ; and  that 
the  lungs,  being  chiefly  supplied  with  nerves  from 
the  eighth  pair,  the  sensorial  power  must,  as  far 


249 


as  regards  them,  cease,  when  that  part  of  the  me- 
dulla oblongata,  from  which  these  nerves  origi- 
nate, and  to  which  all  impressions  communicated 
through  the  spinal  marrow  must  also  be  sent,  is 
destroyed.  The  powers  of  respiration  remain 
after  decapitation,  but  the  sensation  which  ex- 
cites the  animal  to  call  them  into  action  is  gone. 


CHAP.  XII. 

On  the  application  of  the  foregoing  experiments 
and  observations  to  explain  the  nature  and  im- 
prove the  treatment  of  diseases. 

A considerable  length  of  time  alone  can  shew 
how  far  the  principles,  which  seem  to  be  esta- 
blished by  the  experiments  laid  before  the  reader 
in  the  preceding  inquiry,  may  tend  to  improve 
the  knowledge  and  treatment  of  diseases.  It  is 
my  intention,  in  the  present  chapter,  to  point  out 
in  what  instances  they  at  first  view  appear  to  pro- 
mote these  ends.  I shall  begin  with  the  diseases 
which  arise  chiefly  from  a fault  in  the  sanguife- 
rous, afterwards  making  some  observations  on 
those  whose  cause  chiefly  exists  in  the  nervous 
system.  I use  the  qualifying  words  of  the  pre- 
ceding sentence,  because  there  is  hardly  any  dis- 
ease of  the  sanguiferous,  whose  symptoms  do  not 

34 


250 


in  some  degree  depend  on  the  state  of  the  nervous 
system  ; and  on  the  other  hand,  in  almost  all  the 
diseases  of  the  latter,  the  sanguiferous  system  is 
more  or  less  affected.  It  is  evident,  however, 
from  a review  of  the  symptoms  of  these  two  sets  of 
diseases,  that  the  nervous  more  amply  partakes 
of  the  affections  of  the  sanguiferous  system,  than 
the  sanguiferous  of  those  of  the  nervous  system. 
The  cause  of  which  is  sufficiently  evident.  We 
have  found  that  the  circulation  is  immediately 
necessary  to  the  functions  of  the  brain  and  spi- 
nal marrow,  but  that  those  of  the  heart  and  blood 
vessels  may  go  on  for  a certain  length  of  time  af- 
ter the  former  organs  have  ceased  to  exist,  having 
only  on  these  organs  an  indirect  dependence 
through  the  functions  of  respiration  and  secre- 
tion.* 

Of  the  diseases  of  the  sanguiferous  system  there 
are  some  in  which  the  force  of  the  circulation  is 
diminished,  so  that  the  due  supply  of  blood  to  the 
brain  fails,  producing,  according  to  the  degree  in 
which  this  happens,  various  symptoms  of  debility 
or  complete  syncope;  and  others,  in  which  the 
vessels  of  this  organ  are  distended  with  more 
than  their  due  proportion  of  blood,  either  in  con- 
sequence of  the  increased  action  of  the  heart  and 
large  vessels,  or  of  the  vessels  of  the  brain  being  so 

* See  the  experiments  related  in  the  first  chapter  of  this 
part,  and  chap.  10. 


251 


far  weakened  that  their  power  of  resistance  i9  not 
in  due  proportion  to  the  usual  vis  a tergo.  The 
two  last  states  produce  the  same  train  of  symp- 
toms, except  that  in  the  former  the  symptoms  of  a 
morbidly  increased  impetus  of  the  blood  through- 
out the  system  are  more  considerable.*  The  spe- 
cies of  apoplexy  depending  on  these  states  of  the 
sanguiferous  system  is  very  different  from  that 
which  I shall  soon  have  occasion  to  speak  of,  in 
which  the  cause  originates  in  the  brain  itself. 
These  species,  we  shall  find,  are  frequently  com- 
bined, but  when  apoplexy,  from  compression,  ex- 
ists alone,  the  brain  seems  to  re-act  but  little  on  the 
sanguiferous  system.  It  is  observed  above,  that 
I found  by  experiment,  that  considerable  uniform 
pressure  of  the  brain  produces  little  or  no  effect 
on  the  motions  of  the  heart,  f 

* I shall  not  here  enter  on  the  question  how  far  more 
blood  can  exist  in  the  encephalon  at  one  time  than  at  ano- 
ther ; but  only  observe  that,  however  incompressible  the 
brain,  and  immoveable  the  parietes  of  the  head  may  be,  if 
the  brain  is  compressed  by  an  increased  force  of  circulation, 
there  must  then  be  more  blood,  however  little,  in  the  ence- 
phalon than  when  the  brain  is  not  compressed ; and  when 
we  consider  how  many  openings  there  are  in  the  scull,  filled 
only  by  soft  medullary  matter,  we  may  easily  perceive  why 
there  may  exist  within  the  scull  very  evident  accumulations 
of  blood,  without  corresponding  depletion  in  some  other 
parts  of  it,  the  necessity  of  which  certain  anatomists  have 
maintained. 

t Exp.  18. 


252 


Of  Sanguineous  Apoplexy, 

\ The  only  change  which,  in  this  species  of  apo- 
plexy, appears  to  take  place  in  the  action  of  the 
heart,  is,  that  it  becomes  slow  and  oppressed,  as 
if  acting  against  a stronger  opposing  force,  and 
consequently  with  greater  effort  than  usual.  This 
is  easily  accounted  for  by  the  circulation  through 
the  lungs  becoming  more  difficult,  owing  to  the 
muscles  of  respiration  being  less  readily  called 
into  action  in  proportion  as  the  insensibility  in- 
creases, and  the  vessels  of  the  pulmonary  system 
being  less  powerfully  stimulated,  in  proportion 
as  the  blood  less  perfectly  undergoes  the  change 
effected  by  the  air.  But  this  is  not  the  only 
change  which  takes  place  in  the  lungs  in  apo- 
plexy. They  soon  begin  to  be  clogged  with 
phlegm,  which,  in  protracted  cases,  more  than 
the  lessened  action  of  the  muscles  of  respiration, 
at  length  appears  to  occasion  suffocation.  This  is 
readily  explained  by  the  experiments  which  have 
been  laid  before  the  reader,  from  which  it  appears, 
that  when  a considerable  portion  of  the  nervous 
influence  is  withdrawn  from  the  lungs,  the  fluids 
destined  to  form  their  secretions,  being  no  longer 
properly  changed,  accumulate  in  them  till  the  air- 
cells  and  bronchial  tubes  are  so  clogged  that  their 
function  is  at  length  wholly  destroyed-*  Now 


* Exper.  44.  45. 


253 


in  those  cases  of  apoplexy,  in  which  the  brain  is 
so  oppressed  that  the  various  organs  are  deprived 
of  a great  part  of  their  nervous  influence,  but  not 
sufficiently  oppressed  immediately  to  put  a stop  to 
the  action  of  the  muscles  of  respiration,  the  above 
change  necessarily  takes  place  in  the  lungs ; and 
as  they  are  of  more  immediate  importance  to  life 
than  any  other  organ  whose  function  directly  de- 
pends on  the  nervous  system,  this  derangement 
of  the  lungs  is  here  the  cause  of  death.  We  see 
the  patient  to  the  last  endeavouring  to  breathe 
through  the  phlegm  which  clogs  them  and  at 
length  produces  suffocation. 

If  such  be  the  immediate  cause  of  death  in 
sanguineous  apoplexy,  we  have  reason  to  believe, 
from  experiments*  which  have  been  laid  before 
the  reader,  that  by  passing  a stream  of  galvan- 
ism through  the  lungs  they  may  be  enabled  to 
perform  their  functions  for  a longer  time  than 
without  this  aid,  and  thus  the  life  of  the  patient 
for  a certain  time  preserved.  There  is  an  evident 
limit  to  this  effect  of  galvanism.  It  is  only  while 
the  sensibility  continues  such  as  to  induce  the  pa- 
tient to  expand  his  chest  to  a certain  extent  and 
with  a certain  frequency  that  advantage  can  arise 
from  it.  Whatever  be  the  supply  of  nervous  in- 
fluence in  the  lungs,  if  the  air  is  not  admitted 
with  sufficient  frequency,  the  proper  changes,  it 
is  evident,  cannot  go  on.  Galvanism,  under  these 


Exper.  46,  47,  48.  49. 


circumstances,  must  fail  to  relieve  the  breathing, 
having  no  other  effect  but  that  of  a stimulus  in 
promoting  the  sensorial  functions.* 

On  employing  galvanism  in  apoplexy,  I had 
the  satisfaction  to  see  the  foregoing  observations 
confirmed.  After  the  rattling  breathing  had  come 
on,  and  the  patient  seemed  about  to  be  suffocated, 
he  was  at  least  a dozen  times  made  to  breathe 
with  ease,  the  accumulation  of  phlegm  gradually 
disappearing  on  the  application  of  galvanism,  by 
which  his  life  was  evidently  prolonged.  The 
inspirations  about  an  hour  and  an  half  or  two 
hours  before  death,  becoming  very  imperfect  and 
less  frequent,  the  galvanism  failed  to  relieve  him. 
The  relief  obtained,  as  may  be  supposed  from 
what  has  been  said,  was  always  of  very  short 
duration,  the  breathing  sometimes  becoming  op- 
pressed as  soon  as  the  galvanism  was  discon- 
tinued. I directed  it  never  to  be  applied  for 
more  than  ten  minutes  at  a time,  and  no  greater 
power  to  be  employed  than  what  I had  found  a 
person  in  health  could  bear  without  inconveni- 
ence. It  appears  from  the  experiments  which 
have  been  laid  before  the  reader,  that  a long 
continued  and  powerful  application  of  galvanism 
excites  inflammation.  Its  proper  use  in  the  case 
before  us  will  appear  from  what  I shall  have  oc- 
casion to  say  of  asthma  and  suspended  animation. 

* See  the  observations  on  the  office  of  the  sensorial  power 
in  respiration,  in  chap.  10. 


255 


It  is  evident,  from  the  above  observations,  that 
the  use  of  galvanism  is  not  suggested  as  a means 
of  cure  in  apoplexy ; but  it  will  always,  I believe, 
in  the  species  of  this  disease  which  we  are  con- 
sidering, prolong  the  patient’s  life ; and  may  thus, 
under  certain  circumstances,  by  giving  more  time 
for  the  use  of  those  means  which  tend  to  remove 
the  cause  of  the  disease,  be  indirectly  the  means 
of  saving  it. 

Such  are  the  observations  which  are  suggested 
by  the  experiments  which  have  been  laid  before 
the  reader,  respecting  the  action  of  the  heart  and 
the  state  of  the  breathing  in  sanguineous  apoplexy. 
The  character  of  this  species  of  apoplexy  seems 
evidently  to  arise  from  the  power  of  the  heart 
being  independent  of  the  brain,  so  that  the  action 
of  the  former  seems  to  be  no  otherwise  affected 
by  the  state  of  the  latter,  than  necessarily  arises 
from  impeded  respiration.*  These  observations, 
we  shall  find,  by  no  means  apply  to  all  species 
of  apoplexy. 

With  regard  to  the  other  symptoms  of  sangui- 
neous apoplexy,  we  have  seen  it  proved  by  direct 
experiment,  that  the  loss  of  power  in  the  limbs 
does  not  here  arise  from  any  change  having  taken 
place  in  their  muscles,  whose  power  seems  equally 
unimpaired!  with  the  muscles  of  involuntary  mo- 
tion; but  from  the  nervous  influence,  the  only 


Page  220  & seq.  f Exper.  32,  and  p.  97. 


256 


stimulus  of  the  former  being  no  longer  applied 
to  them.  The  urine  and  fseces  often  pass  invo- 
luntarily, not  that  any  change  is  produced  in  the 
sphincters  of  the  bladder  and  rectum,  but  because 
these  being  muscles  wholly  of  voluntary  motion,* 
although  they  still  retain  that  degree  of  contrac- 
tion which  constitutes  their  state  of  rest,  when 
the  pressure  from  within  increases,  as  all  stimu- 
lus supplied  to  them  by  the  powers  of  volition  is 
withdrawn,  they  yield  to  this  pressure. 

The  species  of  apoplexy  which  we  have  been 
considering,  is  the  most  favourable.  By  the  ab- 
straction of  blood  the  brain  is  relieved  from  pres- 
sure, and  its  functions  are  restored,  and  continue, 
unless,  as  frequently  happens,  especially  where 
the  patient  has  suffered  from  previous  attacks  of 
the  disease,  the  vessels  again  yield  to  the  vis  a 
tergo.  We  thus  often  see  the  symptoms  relieved 
by  blood  letting,  but  soon  recur,  and  continue  to 
do  so  till  the  powers  of  the  constitution  are  ex- 
hausted. 

There  are  two  species  of  apoplexy,  proceeding 
from  the  same  cause  with  the  disease  we  are  con- 
sidering, but  very  different  both  in  their  nature 
and  prognosis  ; I mean  those  in  which  the  dis- 
tension of  the  vessels  has  occasioned  rupture,  or 
an  effusion  of  serum.  These  cases,  of  a much 

* Observations  similar  to  those  which  have  been  made 
respecting  the  muscles  of  inspiration  apply  to  the  sphincters. 
Page  222  & seq. 


257 


more  fatal  tendency,  are  distinguished  from  those 
of  mere  distension,  with  great  difficulty.  The  only 
diagnostics  on  which,  it  has  appeared  to  me,  we 
can  rely,  are,  that  in  the  two  first  cases,  particu- 
larly in  the  first,  the  symptoms  generally  encrease 
more  rapidly  than  in  apoplexy  from  mere  disten- 
sion, and  are  little,  if  at  all,  relieved  by  blood 
letting-  That  form  of  serous  apoplexy,  which  is 
the  effect  of  general  debility,  and  takes  place  with 
little  or  no  congestion  of  the  vessels  of  the  brain, 
may,  for  the  most  part,  be  distinguished  by  the 
habit  of  the  patient,  and  by  the  tendency,  to  effu- 
sion in  other  parts.  To  enter  further  on  these 
cases,  and  the  diagnosis  between  them  and  the 
different  forms  of  hydrencephalus,  would  be  fo- 
reign to  my  present  purpose.  I have  enumerat- 
ed them  that  the  reader  may  the  more  clearly  un- 
derstand what  I mean  by  nervous  apoplexy,  on 
which  I shall  soon  have  occasion  to  make  some 
observations. 

It  will  be  necessary  here  to  say  more  of  ano- 
ther affection  of  the  head  which  insensibly  runs 
into  apoplexy  from  distension.  I mean  plirenitis. 
In  both  we  find  the  vessels  of  the  brain  preter- 
naturally  distended,  and  in  many  cases  can  de- 
tect no  other  morbid  appearance ; yet  their  na- 
ture must  essentially  differ.  In  the  one,  the  pa- 
tient often  resembles  a furious  maniac,  while  in- 
sensibility is  always  the  characteristic  of  the  other. 
This  subject  leads  me  to  consider  the  mostimpor- 

35 


358 


tant  of  all  the  diseases  of  the  sanguiferous  system, 
perhaps  I may  say,  of  all  the  diseases  to  which 
we  are  liable. 

Of  Inflammation. 

I endeavoured  many  years  ago  to  ascertain  the 
state  of  the  vessels  in  the  various  stages  of  inflam- 
mation, both  in  the  warm  and  cold  blooded  ani- 
mal, by  observing  them  with  the  assistance  of  the 
microscope.  After  stating  briefly  the  points  which 
appear  to  be  ascertained  by  these  experiments,  a 
detailed  account  of  which,  I have  already  had  oc- 
casion to  observe,  is  given  in  the  Introduction  to 
the  second  part  of  my  treatise  on  Febrile  Diseases, 
I shall  endeavour  to  ascertain  from  the  result  of 
experiments  which  have  been  laid  before  the 
reader  in  the  preceding  Inquiry,  what  share  the 
nervous  system  has  in  producing  the  symptoms 
of  this  disease. 

In  the  first  experiment  on  the  vessels,  the  in- 
flamed web  of  the  foot  of  a frog  was  brought  be- 
fore a microscope ; and  it  was  observed,  that 
where  the  inflammation  was  greatest,  the  vessels 
were  most  distended,  and  the  motion  of  the  blood 
was  slowest.  The  distension  of  the  vessels  which 
in  the  healthy  state  admit  only  the  colourless  part 
of  the  blood  was  apparent,  for  a much  greater 
number  of  vessels  admitted  the  red  particles  in 
the  inflamed  than  in  the  sound  part,  and  the  in- 


359 


terstices  of  the  inflamed  vessels  appeared  more 
opake,  either  from  the  enlargement  of  innumera- 
ble small  vessels,  still  too  small  to  admit  the 
grosser  parts  of  the  blood,  or  from  an  effusion  of 
its  more  colourless  parts.*  With  a view  to  ex- 
cite the  vessels  of  the  inflamed  part,  I wetted  it 
with  spirits,  and  directed  on  it  the  concentrated 
rays  of  the  sun  from  the  concave  reflector  of  the 
microscope.  In  proportion  as  I succeeded  by 
these  means  in  increasing  the  velocity  of  the 
blood,  the  diameters  of  the  vessels  were  dimi- 
nished, their  interstices  became  more  transpa- 
rent, and  the  appearance  of  inflammation  was  in 
the  same  proportion  lessened. 

In  the  second  experiment  I observed  the  in- 
flammation from  its  commencement.  The  fins 
and  tail  of  the  lampern  became  inflamed  by  ex- 
posure to  air.  By  bringing  the  former  before  the 
microscope,  I observed  the  circulation  became 
more  languid  and  the  vessels  enlarge  as  the  in- 

* Dr.  Lubbock,  and  Mr.  Allen,  without  having  made  any 
experiments  on  the  subject,  and  guided  merely  by  the  phe- 
nomena of  the  disease,  maintained,  about  the  year  1790,  that 
inflammation  arises  from  a debility  of  the  vessels  of  the  part. 
Some  hints  of  this  opinion  are  to  be  found  in  writings  of  an 
earlier  date,  but  the  above  gentlemen,  in  the  discussions  of 
the  Medical  Society  of  Edinburgh,  were  the  first  who 
brought  it  forward  in  a connected  form.  Neither,  as  far  as 
I know,  has  published  any  thing  on  the  subject ; I cannot, 
therefore,  say  how  far  their  sentiments,  in  the  detail  of  the 
opinion,  correspond  with  mine. 


260 


flammation  came  on.  The  motion  of  the  blood  in 
the  most  inflamed  parts  at  length  ceased  altogether. 
By  gentle  friction  and  the  application  of  distilled 
spirits,  I repeatedly  succeeded  in  accelerating 
the  motion  of  the  blood  in  the  inflamed  parts.  In 
proportion  as  this  happened,  the  vessels  became 
paler,  and  the  inflammation  was  evidently  di- 
minished. 

These  experiments  having  been  made  on  the 
cold  blooded  animal,  the  mesentery  of  the  rabbit 
was  chosen  for  the  subject  of  the  next  experiment. 
The  result  was  still  the  same.  As  soon  as  the 
inflammation  began,  the  vessels  began  to  enlarge, 
and  the  motion  of  the  blood  became  languid; 
these  changes  going  on  till  in  the  most  inflamed 
parts  the  vessels  were  enlarged  to  several  times 
their  original  diameter,  and  the  motion  of  the 
blood  ceased  altogether.  I repeatedly  occasioned 
debility  of  the  capillaries  of  particular  parts  of 
the  mesentery  by  irritating  them,  and  thus  saw 
inflammation  rapidly  excited  by  the  vis  a tergo 
distending  the  debilitated  vessels. 

It  appears  from  these  experiments  that  the  state 
of  the  smaller  vessels  in  an  inflamed  part  is  that 
of  preternatural  distension  and  debility.  That  of 
the  larger  vessels  may  be  ascertained  without  the 
aid  of  the  microscope.  We  readily  perceive,  on 
viewing  an  inflamed  membrane,  that  they  do  not 
suffer  a similar  distension,  and  the  increased  pul- 
sation of  the  arteries  sufficiently  evinces  their  in- 


261 


creased  action.  In  inflammatory  affections  of  the 
jaw  and  the  head  for  example,  a greatly  increas- 
ed action  of  the  maxillary  and  temporal  arteries 
is  readily  perceived  by  the  finger.  It  is  to  be  ob- 
served, however,  that,  although  inflammation,  as 
was  evident  from  the  foregoing  experiments,  begins 
in  the  capillaries,  if  it  continues,  the  circulation 
in  the  smallest  vessels  becoming  very  languid, 
those  immediately  preceding  them  in  the  course 
of  circulation  begin  to  be  distended  and  conse- 
quently debilitated.  Thus,  when  the  lampern  was 
first  exposed  to  the  air,  the  inflammation  in  the 
fins  and  tail  assumed  the  appearance  of  a slight 
blush,  in  which  it  was  difficult  with  the  naked 
eye  to  discover  any  vessels ; but  after  some  time 
had  elapsed,  vessels  of  a considerable  size  were 
seen  passing  through  the  inflamed  parts.  It  is 
evident  that  this  cannot  go  very  far,  because  when 
the  arteries  preceding  the  capillaries  have  lost 
their  power,  the  circulation  is  no  longer  in  any 
degree  supported  in  the  latter,  and  gangrene  soon 
ensues. 

The  difference  between  what  is  called  active 
and  passive  inflammation  seems  to  depend  on  the 
degree  in  which  the  arteries  supplying  the  vis  a 
tergo  to  the  debilitated  vessels  are  excited. 

In  short,  inflammation  seems  to  consist  in  the 
debility  of  the  capillaries,  followed  by  an  increas- 
ed action  of  the  larger  arteries  ; and  is  terminat- 
ed by  resolution,  when  the  capillaries  are  so  far 


262 


excited,  and  ther  larger  arteries  so  far  weakened 
by  the  preternatural  action  of  the  latter,  that  the 
power  of  the  capillaries  is  again  in  due  proportion 
to  the  vis  a tergo. 

Thus  far,  I cannot  help  thinking,  the  nature  of 
inflammation  appears  sufficiently  evident.  The 
motion  of  the  blood  is  retarded  in  the  capillaries 
in  consequence  of  the  debility  induced  on  them, 
an  unusual  obstacle  is  thus  opposed  to  its  motion 
in  the  arteries  preceding  them  in  the  course  of 
circulation,  which  are  thus  excited  to  increased 
action.  Several  difficulties,  however,  remain,  ou 
which  the  experiments  just  related  throw  no  light. 
Why  does  a failure  of  pow  er,  of  small  extent  in 
the  capillaries  of  a vital  part,  strongly  excite,  not 
only  the  larger  arteries  of  the  part  affected,  but 
those  of  the  whole  system ; while  a more  exten- 
sive debility  of  the  capillaries  of  an  external  part 
excites  less  increased  action  in  the  larger  arteries 
of  that  part,  and  often  none  at  all  in  those  of  the 
system  in  general  ? Why  does  inflammation  often 
move  suddenly  from  one  part  to  another,  when 
we  see  no  cause  either  increasing  the  action  of 
the  capillaries  of  the  inflamed  part  or  weakening 
those  of  the  part  now  affected?  Why  does  in- 
flammation often  arise  in  parts  only  sympatheti- 
cally affected,  and  consequently  far  removed  from 
the  offending  cause?  Why  is  inflammation  often 
as  apt  to  spread  to  neighbouring  parts,  between 
which  and  the  part  first  affected  there  is  no  di- 


263 


rect  communication  of  vessels,  as  to  parts  in  con- 
tinuation with  that  part  ? 

These  phenomena,  it  is  evident,  are  referable 
to  the  agency  of  the  nervous  system,  and  seem 
readily  explained  by  the  experiments  which  prove 
that  the  effects  of  both  stimuli  and  sedatives,  act- 
ing through  this  system,  are  felt  by  the  vessels, 
and  that,  independently  of  the  intervention  of  any 
effect  produced  on  the  heart. * Thus  the  irrita- 
tion of  the  nerves  of  the  inflamed  part  may  ex- 
cite the  larger  arteries  of  this  part,  or  of  distant 
parts,  or  of  the  whole  sanguiferous  system.  It 
will,  of  course,  be  most  apt  to  do  so  where  the 
irritation  excited  by  the  inflammation  is  greatest, 
and  consequently  in  the  more  important  vital 
parts.  It  cannot  appear  surprising,  that  inflam- 
mation should  suddenly  cease  in  one  part  and  at- 
tack another,  when  we  know  that  the  nerves  are 
capable  of  exciting  to  due  action  the  capillaries 
of  the  one  part,  and  in  the  other  of  impairing  the 
vigour  of  those  which  have  not  yet  suffered.  In 
the  same  way  we  account  for  parts  only  sympa- 
thetically affected  becoming  inflamed,  and  for  in- 
flammation readily  spreading  to  neighbouring 
parts,  which  always  sympathise,  although  there 
is  no  direct  communication  between  them,  either 
of  vessels  or  nerves. 

From  the  foregoing  view  of  inflammation  the 


* Exp.  27,  28. 


principles  on  which  its  treatment  is  founded  are 
obvious.  All  the  local  means  are  calculated  either 
to  lessen  the  contents  of  the  morbidly  distended 
vessels,  or  to  excite  these  vessels  to  expel  them. 
The  general  means  are  regulated  by  the  effects 
produced  by  the  disease  on  the  more  distant  ves- 
sels, through  the  medium  of  the  nervous  system  : 
the  objects  of  this  part  of  the  treatment  being  nei- 
ther to  allow  the  action  of  these  vessels  to  fall  so 
low  that  it  is  incapable  of  supporting  any  degree 
of  circulation  in  the  debilitated  vessels,  nor  to  be- 
come so  powerful  as  further  to  distend  by  gorg- 
ing them  with  blood.  Thus,  when  the  symptoms 
of  active  inflammation  run  high,  we  lessen  the 
vis  a tergo,  when  gangrene  is  threatened,  we  in- 
crease it. 

When  the  inflammation  is  of  great  extent,  or 
in  a part  of  great  importance,  the  whole  sangui- 
ferous system  appears,  in  consequence  of  the 
impression  made  on  it  through  the  nervous  sys- 
tem, to  embrace  its  contents  with  greateV  force 
than  usual,  apparently  for  the  purpose  of  sup- 
porting the  circulation  in  the  debilitated  part. 
Hence  appears  to  arise  the  hard  pulse,  from  the 
degree  of  which  we  may  generally  j udge  of  the 
degree  of  the  inflammation. 

Mr.  Hunter’s  observations,  in  his  w ork  on  in- 
flammation, as  nearly  correspond  w ith  the  fore- 
going view  of  this  disease,  as  the  unassisted  eye 
and  the  pre-conceived  opinions,  w hich  he  had,  in 


265 


common  with  the  rest  of  the  medical  world,  adopt- 
ed, admit  of.  u The  vessels,”  he  observes,  “ both 
arteries  and  veins,  in  the  inflamed  part,  are  en- 
larged, and  the  part  becomes  visibly  more  vas- 
cular, from  which  we  should  suspect  that  instead 
of  an  increased  contraction,  there  was  rather  what 
would  appear  an  increased  relaxation  of  their 
muscular  powers,  being,  as  we  might  suppose, 
left  to  the  elasticity  entirely.  This  would  be 
reducing  them  to  a state  of  paralysis  simply,  but 
the  power  of  muscular  contraction  would  seem  to 
give  way  in  inflammation,  for  they  certainly  dilate 
more  in  inflammation  than  the  extent  of  the  elastic 
power  would  allow ; and  it  must  also  be  sup- 
posed that  the  elastic  power  of  the  artery  must  be 
dilated  in  the  same  proportion.”  Thus  far  the 
reader  would  suppose  that  Mr.  Hunter  was  de- 
tailing his  observations  for  the  purpose  of  sup- 
porting the  opinion  which  I have  endeavoured  to 
establish.  He  proceeds,  however,  with  the  in- 
genuity which  characterises  all  his  opinions,  to 
an  attempt  to  reconcile  the  foregoing  appearances 
with  the  common  opinion  of  the  nature  of  inflam- 
mation. “ The  contents  of  the  circulation  being 
thrown  out  upon  such  occasions,  would,  from  con- 
sidering it  in  those  lights,  rather  confirm  us  in 
that  opinion,  and  when  we  consider  the  whole  of 
this  as  a necessary  operation  of  nature,  we  must 
suppose  it  something  more  than  simply  a common 

relaxation  ; we  must  suppose  it  an  action  in  the 

36 


266 


parts  to  produce  an  increase  of  size  to  answer  par- 
ticular purposes,  and  this  I should  call  the  action 
of  dilatation,  as  we  see  the  uterus  increase  in  size 
in  the  time  of  uterine  gestation,  as  well  as  the  os 
tincse  in  the  time  of  labour,  the  consequence  of 
the  preceding  actions,  and  necessary  for  the  com- 
pletion of  those  which  are  to  follow.”*  The 
reader  will  perceive  that  all  the  facts  recorded  in 
the  preceding  quotation  are  in  favour  of  the  opi- 
nion I have  defended,  the  explanation  alone  be- 
ing in  opposition  to  it. 

A little  before  Mr.  Hunter  observes,  “ as  the 
vessels  become  larger  and  the  part  becomes  more 
of  the  colour  of  the  blood,  it  is  to  be  supposed 
there  is  more  blood  in  the  part,  and  as  the  true 
inflammatory  colour  is  scarlet,  or  that  colour  which 
the  blood  has  when  in  the  arteries,  one  would  from 
hence  conclude,  either  that  the  arteries  were  prin- 
cipally dilated,  or  at  least,  if  the  veins  are  equally 
distended,  that  the  blood  undergoes  no  change  in 
such  inflammation  in  its  passage  from  the  arteries 
into  the  veins,  which  I think  most  probably  the 
case  ; and  this  may  arise  from  the  quickness  of 
its  passage  through  those  vessels.”  How  diffe- 
rent would  have  been  Mr.  Hunter’s  inferences,  if 
instead  of  trusting  to  the  unassisted  eye,  he  had 
viewed  the  inflamed  vessels  through  the  micro- 

* Mr.  Hunter’s  Treatise  on  the  Blood,  Inflammation  and 
Gunshot  Wounds,  p.  282. 


267 


scope.  He  could  then  have  seen  the  blood  mov- 
ing, and  would  have  found,  that  instead  of  its 
passage  being  quickened  in  the  inflamed  vessels, 
it  is  uniformly  rendered  slower  in  proportion  to 
the  degree  of  the  inflammation,  and  in  the  most 
inflamed  parts,  stands  still  altogether.  I have, 
in  the  part  of  my  treatise  on  fevers  above  referred 
to,  shewn  from  several  facts  ascertained  respecting 
the  colour  of  the  blood,  that,  within  certain  limits, 
the  accumulation  of  this  fluid  in  the  debilitated 
vessels  of  the  inflamed  part  necessarily  causes  the 
blood  to  retain  the  florid  colour. 

It  is  worth  while  to  observe  the  difficulty  which 
Mr.  Hunter  experiences  in  attempting  to  explain, 
on  his  view  of  inflammation,  the  cause  of  the 
throbbing  pain  of  an  inflamed  part,  which  is  evi- 
dently a necessary  consequence  of  a debilitated 
and  distended  state  of  the  smaller,  and  increased 
action  of  the  larger  vessels.  “This  pain  in- 
creases,he  observes,  “ every  time  the  arteries 
are  dilated,  whence  it  would  appear  that  the  ar- 
teries do  not  contract  by  their  muscular  power  in 
their  systole,  for  if  they  did  we  might  expect  a 
considerable  pain  in  that  action,  which  would  be 
at  the  full  of  the  pulse.  Whether  this  pain  arises 
from  the  distension  of  the  artery  by  the  force  of 
the  heart,  or  whether  it  arises  from  the  action  of 
distension  from  the  force  of  the  artery  itself,  is 
not  easily  determined;  we  know  that  diseased 


268 


muscles  give  much  pain  in  their  contraction,  per- 
haps more  than  they  do  when  stretched.”* 

Dr.  Parry,  in  his  Elements  of  Pathology  and 
Therapeutics,  takes  a view  of  the  nature  of  in- 
flammation, as  far  as  I kuow,  peculiar  to  himself. 
He  makes  the  following  observations  on  the  opi- 
nion of  inflammation,  which  I had  endeavoured 
to  support  in  the  treatise  just  referred  to.  “ Nei- 
ther will  this  conclusion  be  invalidated  were  it 
even  proved,  according  to  the  opinion  of  Dr.  Wil- 
son, that  the  velocity  of  the  blood  in  the  vessels 
of  an  inflamed  part  is  diminished,  unless  it  be  also 
proved  that  the  velocity  is  diminished  in  a greater 
proportion  than  the  quantity  is  increased.”f  Ac- 
cording to  Dr.  Parry’s  view  of  the  nature  of  in- 
flammation it  consists  in  an  increased  momentum 
of  the  blood  in  an  inflamed  part.  I should  be 
happy  to  consider  particularly  every  step  of  the 
ingenious,  though,  as  it  appears  to  me,  fallacious 
train  of  reasoning,  by  which  he  arrives  at  that 
conclusion.  But  as  this  would  lead  into  a dis- 
cussion of  considerable  length,  I shall  confine  my- 
self to  the  statement  of  such  facts  as  appear  to  be 
incompatible  with  it.J 

As  Dr.  Parry  admits  that  there  is  a greater 


* Page  287.  t Vol.  1.  p.  84. 

t Some  of  the  observations  which  I am  about  to  make 
were  published  in  the  sixth  volume  of  the  Medical  Repository. 


269 


quantity  of  blood  in  the  vessels  of  an  inflamed 
part  than  in  the  same  part  when  sound,  he  admits 
that  the  vessels  in  inflammation  are  morbidly  dis- 
tended, the  necessary  inference  from  which  is 
that  their  power  is  lessened.  This  inference  did 
not  escape  Dr.  Parry,  but  he  maintains,  in  the 
198th  paragraph,  that  the  blood  is  moved  in  the 
capillary  vessels  not  by  the  power  of  these  ves- 
sels, but  by  the  impulse  it  receives  from  the  heart. 

This  opinion  it  is  not  difficult  to  submit  to  the 
test  of  direct  experiment.  We  have  seen  it  as- 
certained by  the  assistance  of  the  microscope, 
both  in  warm  and  cold  blooded  animals,  that  the 
motion  of  the  blood  in  the  smaller  vessels  conti- 
nues for  a long  time  after  what  we  call  death,  al- 
though immediately  after  it,  a ligature  be  thrown 
round  all  the  vessels  attached  to  the  heart.*  Dr. 
Parry  ascribes  the  continuance  of  the  motion  of 
the  blood  in  the  capillaries,  in  certain  experi- 
ments of  Haller,  after  the  aorta  had  been  secured 
by  ligature  and  removed  from  the  heart,  to  the 
contractile  power  of  the  larger  arteries  ; and  he 
has,  in  a work  published  since  that  above  refer- 
red to,  entitled  u An  Experimental  Inquiry  into 
the  Nature,  Cause  and  Varieties  of  the  Arte- 
rial Pulse,  «fc.”  made  many  interesting  experi- 
ments for  the  purpose  of  ascertaining  the  degree 
of  this  power.  That  something  must  here  be  as- 


* Exp.  24,  25,  75,  76, 


270 


cribed  to  it,  cannot,  I think,  be  denied ; but  that 
the  motion  of  the  blood  in  the  capillaries  chiefly 
depends  on  their  own  powers,  appears  from  the 
following  facts,  which  I have  ascertained  by  re- 
peated experiments. 

When  the  power  of  the  capillaries  is  destroyed, 
the  vis  a tergo,  even  in  the  living  animal,  as  the 
reader  has  seen  in  the  experiments  on  the  state 
of  inflamed  vessels,  is  not  capable  of  propelling 
the  blood  through  them.  As  the  motion  of  the 
blood  in  the  smaller  vessels  begins  to  fail,  where 
there  is  no  inflammation,  either  in  the  living  or  in 
the  dead  animal,  it  is  observed  to  stop  and  go  on, 
to  move  backwards  and  forwards  in  the  same 
vessel  and  to  stop  in  some  vessels  of  the  same 
part  sooner  than  in  others,  phenomena  which  it  is 
evident,  could  not  arise  from  the  contractile 
power  of  the  larger  arteries.  I have  laid  before 
the  reader  many  experiments  of  a different  na- 
ture, the  results  of  Avhich  appear  to  be  wholly  in- 
compatible with  the  opinion  of  Dr.  Parry,  and 
which  seem  to  me  to  prove,  in  the  most  unequivo- 
cal manner,  that  the  motion  of  the  blood  in  the 
capillaries  neither  depends  on  the  impetus  given 
to  it  by  the  heart,  nor  on  the  contractility  of  the 
larger  vessels.  I wish  the  more  to  insist  on  this 
subject  because  the  authority  of  Dr.  Parry  has, 
with  many,  given  a currency  to  his  opinion.  Can 
all  contractility  of  the  larger  arteries,  the  greater 
part  of  which  according  to  Dr.  Parry’s  experi- 


271 


ments  consists  in  the  mere  property  of  elasticity, 
be  destroyed  by  crushing  the  brain  or  spinal  mar- 
row ? We  find,  from  experiments  29,  and  30, 
that  the  immediate  effects  of  crushing  either,  is 
that  of  instantly  destroying  the  circulation  in  the 
capillaries.  In  these  experiments,  it  is  true,  no 
ligature  was  thrown  round  the  vessels  attached  to 
the  heart,  but  the  result  could  not  arise  from  loss 
of  power  in  that  organ,  because  the  total  removal 
of  it,  either  in  the  warm  or  cold-blooded  animal, 
produces  no  such  effect.  (Exp.  2%  75,  76.)  It 
is  an  effect  altogether  analogous  to  what  takes 
place  in  the  heart  itself,  from  the  same  cause. 
(Exp.  20,  21.)  When  tobacco  was  applied  to 
the  brain,  the  motion  of  the  blood  in  the  capilla- 
ries was  lessened  and  soon  ceased.  (Exp.  26, 
27.)  Can  we  ascribe  this  to  the  diminished  ac- 
tion of  the  heart?  Its  total  removal,  we  have  just 
seen,  produces  no  such  effect.  Nobody  will  main- 
tain that  it  is  to  be  ascribed  to  the  tobacco,  applied 
to  the  brain,  destroying  all  contractility  in  the 
larger  arteries.  Is  it  possible,  from  these  expe- 
riments, to  make  any  other  inference  than  that 
the  capillaries  possess  a power  similar  to  that  of 
the  heart,  which  is  influenced  by  affections  of  the 
nervous  system  in  the  same  way?  Page  243  (46). 

The  motion  of  the  blood  in  the  capillaries,  after 
visible  death,  seems  so  far  from  depending  on  the 
elasticity  of  the  larger  arteries,  that,  as  far  as  I 


am  capable  of  judging,  the  emptiness  of  these  ar- 
teries after  death,  may  be  shewn  to  arise  from  the 
continued  action  of  the  former  set  of  vessels. 

Dr.  Parry  found  that  the  larger  arteries  have 
their  diameter  lessened  after  death,  but  that  it 
again  enlarges,  though  not  to  the  same  extent.  I 
should  be  inclined  to  explain  these  phenomena, 
if,  indeed,  they  at  all  obtain  in  a sensible  degree, 
except  when  the  artery  is  exposed  to  the  influ- 
ence of  the  air,  in  a way  different  from  that  pro- 
posed by  Dr.  Parry.  We  must  suppose,  I think, 
from  the  facts  just  mentioned,  that  the  action  of 
the  capillaries  combines  with  the  contractile  power 
of  the  larger  arteries,  in  lessening  the  contents  of 
the  latter.  As  long  as  these  contents  are  of  suf- 
ficient bulk  to  stimulate  the  vessel,  it  will  closely 
embrace  them,  and  thus  as  its  contents  are  les- 
sened, contract  beyond  the  effects  of  its  elasticity; 
but  by  the  continued  action  of  the  capillaries,  the 
bulk  of  these  contents  at  length  becoming  too 
small  to  stimulate  the  vessel,  it  will  be  relaxed, 
and  thus,  by  its  elastic  power,  regain  a larger 
diameter.  I have  already  had  occasion  to  make 
some  observations  on  this  subject,*  and  to  remark 
how  readily  the  continued  action  of  the  capilla- 
ries, after  that  of  the  heart  has  ceased,  may  lessen 
the  contents  of  the  larger  vessels,  vessels  in  di- 


273 


viding  into  branches,  having  the  sum  of  their  areas 
increased.  That  the  emptiness  of  the  arteries 
after  death,  for  they  are  sometimes  found  quite 
empty,  does  not  arise  from  their  contractile  power, 
as  Dr.  Parry  supposes,  appears  even  from  his  own 
very  accurate  experiments.  They  do  not  teach  us 
that  the  contraction  of  the  arteries  after  death  is 
sufficient  to  obliterate  their  cavities,  and  no  less 
degree  of  it,  it  is  evident,  can  wholly  expel  their 
contents. 

With  respect  to  some  other  inferences  which 
Dr.  Parry  makes  from  his  experiments,  I think 
he  will  admit,  that  we  may  be  deceived  respect- 
ing the  usual  action  of  the  arteries,  by  dividing 
and  making  other  experiments  on  them,  while 
exposed  to  the  air,  which  applies  a peculiarly 
strong  stimulus  to  parts  not  usually  subjected  to 
its  action.  If  the  abdomen  of  a warm  blooded 
animal  be  opened  soon  after  death,  although  the 
usual  effect  is  an  increase  of  the  peristaltic  motion 
in  those  parts  of  the  intestines  which  are  exposed 
to  the  air,  sometimes  they  fall  into  a state  of  per- 
manent contraction,  and  in  this  state  remain  mo- 
tionless. May  not  such  a permanent  contraction, 
existing  in  so  small  a degree  as  to  escape  obser- 
vation, be  the  cause  of  Dr.  Parry’s  not  having 
observed  any  alternate  contraction  and  dilatation 
in  the.  exposed  arteries?  Arteries  are  often  very 
evidently  lessened  in  diameter,  and  sometimes 
37 


thrown  into  strong  partial  contractions  by  expo- 
sure to  the  air.*  It  must  however,  be  admitted, 
I think,  that  the  pulse  is  chieflyf  caused  in  the 
way  Dr.  Parry  has  so  well  explained.  The 
beatings  of  the  arteries  of  rabbits,  observed  in 
my  experiments,  were  probably  of  the  same  na- 
ture with  the  motion  of  the  arteries  corresponding 
to  the  contractions  of  the  ventricle  observed  by 

* See  Dr.  Parry’s  13th,  24th,  and  26th  experiments,  and 
the  account  of  an  experiment  of  Vershuir  in  Dr.  Fowler’s 
Thesis  on  Inflammation.  I have  frequently  observed  a ge- 
neral lessening  of  an  artery  on  its  exposure  to  the  air. 

t The  word  chiefly,  as  here  used,  seems  to  require  some 
explanation.  All  admit  that  the  arteries  are  elastic  tubes, 
and  it  will  not  be  denied  that  the  larger  arteries  are  exposed 
to  a more  powerful  distending  force  during  the  systole  than 
during  the  diastole  of  the  heart.  It  necessarily  follows, 
therefore,  that  these  arteries  are  more  distended  during  the 
former  than  during  the  latter,  even  on  the  supposition  that 
the  increased  stimulus  of  distension  excites  no  vital  action 
in  them.  Whether  the  increased  distension  is  in  such  a 
degree  as  to  be  sensible, is  another  question.  The  experi- 
ments of  Dr.  Parry  prove  that  it  is  not  sensible  to  the  eye 
when  the  artery  is  exposed.  That  it  is  sensible  to  the  toucli 
appears,  I think,  from  the  circumstance,  that  when  the  cir- 
culation is  vigorous,  the  pulse  is  sensible  to  pressure  too 
slight  to  influence  the  calibre  of  the  artery.  It  is  sensible 
to  the  slightest  touch:  but  that  the  sensation  produced  in 
the  finger  in  feeling  the  pulse,  is  excited  chiefly  in  the  way 
Dr.  Parry  has  explained,  appears  from  its  increasing  with 
the  pressure  until  the  latter  becomes  such  as  nearly  to  obli- 
terate the  cavity  of  the  artery. 


275 


Dr.  Parry.  This  motion  of  arteries  may  often 
be  seen  in  the  human  body,  in  the  wrists,  the 
temples,  and  the  neck,  while  the  skin  is  entire. 

When  we  consider  attentively  the  results  of 
the  various  experiments  to  which  I have  refer- 
red, does  it  not  seem  a necessary  inference,  that 
the  blood  is  moved  in  the  capillaries  by  the  power 
of  these  vessels  themselves;  and,  consequently, 
that  if  they  are  debilitated,  the  momentum  of  the 
whole  blood  in  the  part,  as  well  as  its  velocity, 
must  be  less  than  in  health  ? The  truth  of  this  in- 
ference appears,  indeed,  from  direct  experiments ; 
for  from  those  made  with  a view  to  ascertain  the 
state  of  the  vessels  in  an  inflamed  part,  of  which 
an  account  lias  been  given,  it  clearly  appears,  not 
only  that  the  velocity  of  every  part  of  the  blood 
was  lessened,  which  Dr.  Parry  admits  may  be 
the  case,  supposing  the  lessened  momentum,  aris- 
ing from  this  cause,  more  than  compensated  by 
the  increased  quantity  of  blood,  but  that  the  ge- 
neral momentum  of  the  blood  also  in  the  inflamed 
part  was  lessened;  because  the  blood  was  ob- 
served to  move  more  and  more  slowly,  till  in  the 
most  inflamed  parts  it  ceased  to  move  altogether. 
Now  before  the  momentum  of  the  blood  in  those 
parts  was  wholly  lost,  it  must  have  passed  through 
all  the  degrees  between  the  healthy  momentum 
and  none ; during  which  the  part  exhibited  the 
phenomena  of  inflammation. 

In  the  introduction  above  referred  to,  I have 


276 


pointed  out  in  detail,  that  the  view  of  inflamma- 
tion there  taken  is  supported  by  the  various  phe- 
nomena of  that  disease. 

We  may  easily,  I think,  from  what  has  been 
said,  perceive  the  steps  by  which  inflammation 
terminates  in  resolution  and  in  gangrene.  In 
the  one  case  the  debilitated  capillaries  are  excited 
to  due  action  by  the  increased  action  of  the  larger 
arteries  ; in  the  other  the  increased  stimulus  fail- 
ing to  produce  this  effect,  the  capillaries  wholly 
lose  their  power,  and  the  part  becomes  subject 
to  the  laws  of  dead  matter.  The  process  of  sup- 
puration is  more  complicated,  and  between  the  in- 
ferences from  the  experiments  which  have  been 
related  respecting  the  state  of  the  vessels  in  an 
inflamed  part,  and  those  afforded  by  the  experi- 
ments of  Mr.  now  Sir  Everard  Home,*  on  the 
formation  of  pus,  related  in  his  valuable  Treatise 
on  this  fluid,  there  is  a chasm,  which  must  be  filled 
up  by  future  observation.  It  appears  from  what 
has  been  said,  compared  with  the  experiments  of 
Sir  Everard  Home,  that  when  the  capillary  ves- 
sels of  a part  remain  for  a certain  length  of  time 
in  a state  of  debility  and  distension,  it  often  be- 
gins to  secrete  a fluid  which  becomes  pus ; for  Sir 

* A Treatise  on  the  properties  of  Pus,  bj  Everard  Home, 
Esq.  4to.  London,  1788.  This  Treatise  was  republished  in 
1797,  in  his  work  on  Ulcers. 


277 

Everard  has  shewn  that  this  fluid  has  not  the 
purulent  appearance  when  first  secreted,  but  ac- 
quires it  while  it  remains  on  the  inflamed  surface, 
and  does  not  acquire  it  the  less  readily  when  re- 
moved from  that  surface  in  a colourless  state,  pro- 
vided its  proper  temperature  be  preserved,  and  it 
is  equally  exposed  to  the  influence  of  the  air, 
which  promotes  the  change.  He  has,  in  the 
above  publication,  thrown  great  light  on  the  pa- 
thology of  some  of  the  most  important  internal  dis- 
eases, by  showing  how  readily  pus  is  formed  by 
secreting  surfaces  independently  of  any  breach  of 
substance.  He  found  it  completely  formed  by 
causes  of  irritation  applied  to  such  surfaces  in  the 
short  space  of  five  hours.  Whether  this  fluid  is 
secreted  from  the  contents  of  the  original  vessels, 
or,  as  Mr.  Hunter  supposes,  of  anew  set  of  vessels 
formed  in  the  diseased  part,  we  cannot  tell.  We 
are  also  unacquainted  with  the  nature  of  the  pro- 
cess by  which  the  diseased  parts  are  removed  in 
the  formation  of  abscess.  We  know  not  whether 
it  be  by  an  increased  action  of  the  absorbents  of 
the  part,  or  by  the  action  of  vessels  formed  for  the 
purpose.  We  cannot  suppose  that  the  diseased 
parts  are  melted  down  and  assimilated  into  its 
own  nature  by  the  action  of  pus,  an  opinion  at 
one  time  prevalent,  since  we  find  that  this  fluid 
with  all  its  properties  may  be  formed  by  inflamed 
surfaces,  without  any  loss  of  substance  taking 
place,  and  it  more  directly  appears  from  the  ex- 


periments  of  Sir  Everard  Home,  that  it  does  not 
possess  the  property  of  eroding  the  solids.  These 
topics  open  a fruitful  and  interesting  field  of  in- 
quiry. By  patient  observation,  and  the  aid  of 
glasses,  it  is  not  improbable,  in  the  present  im- 
proved state  of  chemistry,  that  the  whole  process 
of  suppuration  might  be  unfolded. 

When  the  larger  vessels  of  a part  are  debili- 
tated and  consequently  distended  without  previous 
distension  of  the  capillaries ; the  disease,  which 
may  be  termed  congestion  or  partial  plethora,  is 
of  a nature  very  different  from  inflammation.  In 
this  case  there  is  little  or  no  distension  of  the  ca- 
pillaries, as  appears  from  their  being  pale  or  only 
slightly  turgid  with  red  blood.  The  vis  a tergo, 
from  the  debilitated  state  of  the  larger  vessels, 
being  too  weak  greatly  to  distend  them,  they  more 
or  less  perfectly  retain  their  power,  and  as  long 
as  the  larger  vessels  can  afford  any  supply  of 
blood,  preserve  the  circulation,  as  it  appears  from 
what  has  just  been  said,  they  are  capable  of  do- 
ing both  in  the  warm  and  cold  blooded  animal, 
long  after  the  effect  of  the  powers  of  the  larger 
vessels  has  ceased.  Such  appears  to  be  the  state 
of  the  vessels  of  the  brain  in  sanguineous  apo- 
plexy, while  in  phrenitis  the  larger  vessels  are 
comparatively  little  distended,  the  distension  be- 
ing chiefly  in  the  capillaries.  This  difference  is 
evident  on  dissection.  After  the  latter  disease, 
when  it  has  been  distinctly  formed,  a general  blush 


279 


is  observed  in  the  parts  of  the  brain  affected : 
while,  after  the  former,  a preternatural  distension 
of  the  larger  vessels  is  conspicuous,  while  the  brain 
itself  is  often  nearly  or  altogether  of  the  natural 
colour.  It  is  an  observation  of  writers  on  phre  ■ 
nitis,  that  if  coma  supervene  on  delirium  in  this 
disease,  it  is  almost  always  fatal.  The  cause  of 
which  is  evident  from  what  has  been  said.  If, 
while  the  capillaries  are  debilitated,  the  larger 
vessels,  to  a considerable  degree,  also  lose  their 
power,  the  circulation  in  the  former  must  wholly 
fail. 

In  other  parts,  as  well  as  in  the  brain,  we  con- 
stantly observe,  that  the  distension  of  the  capilla- 
ries is  attended  with  acute  symptoms,  great  pain 
and  fever,  while  that  of  the  larger  vessels  is  ge- 
nerally attended  with  little  of  either,  being  chiefly 
denoted  by  a failure  in  the  function  of  the  part  af- 
fected. The  cause  of  this  difference  appears  from 
those  experiments  which  prove  that  the  sanguife- 
rous and  nervous  systems  sympathise  in  their  ex- 
treme parts  in  a way  they  are  not  found  to  do  in 
any  other  ;*  which  we  have  reason  to  believe  arises 
from  the  capillaries  supplying  to  the  nervous  in- 
fluence the  fluids  on  which  it  operates  in  the  func- 
tion of  secretion,!  the  failure  of  which  must  ne- 
cessarily occasion  a degree  of  derangement  in  the 


Exper.  44, 45. 


t Chap.  5.  Sect.  S. 


280 


nervous  system,  which  cannot  arise  to  the  same 
degree  from  causes  chiefly  affecting  the  larger  ves- 
sels ; for,  however  debilitated  these  vessels  may 
be,  unless  the  circulation  in  them  fail  altogether, 
in  which  case  the  death  of  the  part  soon  ensues, 
the  capillaries,  as  appears  from  what  has  just  been 
said,  are  still  capable  of  affording  a supply  of 
fluids  to  the  secreting  power.  It  is  probably,  also, 
from  the  copious  supply  of  nervous  influence  sent 
to  the  capillaries  for  the  purpose  of  secretion,  that 
these  vessels  appear  to  be  so  much  more  sensible 
than  the  larger  vessels. 

It  has  long  been  observed  by  physicians  that  the 
inflammation  of  the  same  organ  sometimes  excites 
acute  pain  and  a great  degree  of  fever,  and  in  other 
cases  comparatively  little  of  these  symptoms,  being 
chiefly  remarkable  by  the  lesion  of  function  it  oc- 
casions. Thus,  inflammation  of  the  brain  has  been 
divided  into  two  species — phreuitis  and  phreuis- 
mus ; the  latter  differing  in  no  essential  respect 
from  sanguineous  apoplexy — that  of  the  lungs  into 
pleurisy  and  peripneuinony,  &c.  The  difference 
of  the  symptoms  in  such  cases  has  been  explain- 
ed by  the  supposition  that,  in  the  acute  cases,  the 
membrane  is  affected,  and  in  those  less  acute  the 
parancliima.  Numerous  dissections  have  now 
proved  the  fallacy  of  this  explanation.  The  pa- 
ranchima  alone  having  often  been  found  affected 
in  the  most  acute,  and  the  membranes  alone  in  the 


281 


least  acute  cases.*  I believe  it  will  often  appear 
that  in  the  former  the  capillaries,  in  the  latter  the 
larger  vessels,  are  the  chief  seat  of  the  disease. 
I am  aware  that  this  will  not  always  be  found  to 
be  the  case,  for  the  capillaries  sometimes  suffer 
distension  with  little  or  no  pain,  particularly  where 
the  progress  of  the  disease  is  slow.  In  general, 
however,  in  proportion  as  the  distension  is  con- 
fined to  the  larger  vessels  there  is  less  fever  and 
less  pain,  and  when  they  alone  are  affected  there 
is  little  or  none  of  either. 

* If  the  reader  will  consult  the  20th  Epistle  of  Morgagni, 
Be  sedibus  et  Causis  Morborum,  particularly  the  9th,  33d, 
35th,  39th,  41st,  43d,  47th,  49th  and  62d  sections  of  it,  and 
some  parts  of  his  21st  Epistle,  he  will  find  that  the  symptoms 
regarded  as  peculiar  to  pleurisy  have  frequently  attended  the 
paranchymatous  inflammation  of  the  lungs,  and  that,  when 
the  pleura  was  not  at  all  affected.  When  we  inspect  the 
bodies  of  those  who  die  of  inflammation  of  the  lungs  (says 
Schroeder,  Opusc.  Med.)  they  alone  are  sometimes  found  in- 
flamed, although  the  symptoms  of  pleurisy  had  been  well 
marked.  Petrus  Servius  opened  three  hundred  people  at 
Rome,  who  died  with  the  symptoms  of  pleurisy,  in  which  the 
lungs  were  greatly  inflamed,  the  pleura  little  or  not  at  all. 
Tissot  met  with  similar  cases  ; and  Diemerbroech  says,  that 
in  two  or  three  cases,  in  which  there  had  been  no  acute  pain, 
and  where  consequently,  according  to  the  common  opinion, 
the  paranchyma  of  the  lungs  alone  should  have  been  found 
affected,  the  pleura  equally  partook  of  the  disease.  Burse- 
rius,  observes,  that  dissections  are  not  wanting  to  prove  that 
inflammation  of  the  pleura  has  been  present  without  any  pain. 
Sydenham  seems  to  go  so  far  as  to  believe  the  paranchyma  of 
the  lungs  to  be  very  frequently  the  seat  of  pleurisy.  And 

38 


282 


All  local  diseases  producing  fever,  seem  to  con- 
sist in  debility  of  the  capillary  vessels  of  the  part 
affected.  Dr.  Cullen  arranges  them  all  under 
three  heads,  Inflammation,  Hemorrhagy  and  Pro- 
fluvium.  If  we  examine  the  symptoms  of  the  two 
last  we  shall  find,  that  except  these  diseases  are 
of  a mere  passive  nature,  arising  from  external 
violence  or  extreme  relaxation,  in  which  cases 
they  do  not  excite  fever,  their  symptoms  are  those 
of  inflammation  relieved  by  discharge ; in  the  one 
case,  the  effect  of  rupture  of  the  vessels,  in  the 
other,  apparently  of  distension  of  their  extremi- 
ties ; and  it  is  particularly  to  be  remarked,  that 
it  is  only  in  proportion  as  the  symptoms  of  in- 
flammation prevail,  that  those  of  fever  attend. 
It  seems  then  from  direct  experiment  to  be  a law 

Juncker,  in  his  Conspectus  Pathol ogife,  observes,  that  pleu- 
risy often  passes  into  peripneumony,  by  which  we  may  un- 
derstand that  the  paranchyma  was  found  inflamed  where  the 
symptoms  had  been  those  of  pleurisy  ; for  such  was  the  pre- 
judice in  favour  of  this  division  of  pneumonia,  that  when  it 
was  found  that  the  appearances  on  dissection  did  not  cor- 
respond with  it,  it  has  been  supposed  that  the  one  form  of  the 
disease  had  passed  into  the  other,  an  opinion  which  seems  to 
have  been  sanctioned  even  by  Haller.  Yet  we  find  in  some 
of  the  oldest  writers  more  correct  observations.  Hippocrates 
speaks  of  pleurisy  and  peripneumony  as  affections  of  nearly 
if  not  altogether,  the  same  parts  ; and  Galen  observes  that  the 
pain  in  peripneumony  is  sometimes  acute.  Many  observa- 
tions to  the  same  effect  might  be  added  from  authors  of  equal 
authority,  both  with  respect  to  the  disease  we  are  speaking 
of,  and  inflammatory  affections  of  other  organs. 


283 


of  the  animal  economy,  that  debility  of  the  capil- 
lary vessels,  and  this  alone  of  all  local  affections, 
applies  to  the  nervous  system,  such  an  irritation 
as  excites  to  preternatural  action  the  larger  ves- 
sels of  the  part,  and  when  of  great  extent  or  in 
vital  parts,  the  whole  sanguiferous  system. 

Do  these  observations  throw  any  light  on  the 
nature  of  fever  properly  so  called  ? In  this  dis- 
ease we  find  a general  debility  of  the  capillaries 
followed  by  an  increased  action  of  the  hpart  and 
larger  vessels,  its  symptoms  subsiding  as  soon  as 
the  capillaries  are  excited  to  the  due  performance 
of  their  functions.  In  such  a state  of  the  sangui- 
ferous system,  it  is  evident,  that  debilitating 
causes,  acting  partially,  will  readily  increase  the 
debility  of  the  capillaries  affected  by  them,  and 
thus,  as  appears  from  what  has  been  said,  excite 
inflammation,  which  will  either  run  its  usual 
course  or  be  relieved  by  liemorrhagy  or  proflu- 
viurn.  May  we  not  thus  account  for  the  frequency 
of  these  affections  in  fever? 

In  this  disease,  inflammation  is  particularly  apt 
to  arise  in  the  brain,  because  the  blood  being  re- 
turned thence,  by  membraneous  canals,  which 
cannot  partake  of  the  increased  excitement  of  the 
central  parts  of  the  sanguiferous  system,*  this  ex- 

* The  final  cause  of  this  structure  appears  to  be  to  supply 
a greater  temporary  vigour  on  various  occasions  where  the 
s apidity  of  the  circulation  is  increased,  particularly  where 


284 


citement  necessarily  tends  to  occasion  accumula- 
tion of  blood  there.  Inflammation  is  also  apt  to 
occur  in  fever  in  those  parts  where  the  vessels  are 
most  numerous  and  delicate,  and  where  they  are 
exposed  to  any  species  of  injury  ; that  is,  where 
they  are  most  apt  to  be  debilitated. 

According  to  this  view  of  the  subject,  fever 
must  be  regarded  as  a state  of  general  iuflamma* 
tion,  the  symptoms  peculiar  to  inflammation  not 
appearing  in  any  great  degree,  only  because  the 
increased  vis  a tergo,  being  so  much  smaller  in 
proportion  to  the  number  of,  and  consequently  the 
resistance  opposed  by,  the  debilitated  vessels, 
than  in  inflammation  where  the  vessels  of  only 
one  part  are  debilitated,  that  it  cannot  greatly 
distend  them,  and  consequently,  excite  the  more 
prominent  symptoms  of  inflammation,  unless  they 
become  particularly  debilitated  in  some  one  part ; 
but  it  often  excites  all  these  symptoms  in  a less 
degree,  increase  of  heat,  redness  and  fullness  of 
the  various  surfaces.  I may  observe  also,  that  in 
proportion  as  these  symptoms  appear  the  pulse  be- 
comes hard  as  in  inflammation,  aud  the  bufly  coat 
shews  itself  on  the  blood.  Are  not  all  the  other 
symptoms  of  fever  equally  the  consequences  of 

great  efforts  are  made,  and  consequently  great  excitement  re- 
quired in  the  muscles  of  voluntary  motion  ; all  organs  be- 
ing, within  certain  limits,  more  or  less  vigorous  according 
to  the  quantity  of  blood  circulating  in  them. 


285 


this  state  of  the  circulation,  the  symptoms  of  ex- 
citement arising  from  the  general  effort  of  the  san- 
guiferous system  to  excite  the  capillaries,  those  of 
debility  from  the  state  of  the  latter  vessels,  and 
the  consequences  of  the  ineffectual  or  but  partially 
successful  efforts  to  restore  their  due  action  ? It 
is  evident  from  what  has  been  said,  that  the  ner- 
vous is,  equally  with  the  sanguiferous  system, 
engaged  in  these  efforts. 

In  what  may  be  called  the  local  treatment  of 
fever  we  find,  that  causes  exciting  the  capillaries 
of  any  considerable  part  with  which  others  sym- 
pathise, the  sudden  application  of  cold  to  the  sur- 
face, the  effect  of  cathartics  in  the  alimentary  ca- 
nal, &c.  tend  to  relieve  this  disease. 

With  respect  to  the  general  treatment,  as  the 
whole  of  the  capillaries  are  debilitated,  and  the 
increased  vis  a tergo  consequently  bears  a less 
proportion  to  the  resisting  force  than  in  inflam- 
mation, it  requires  less  reduction ; but  as  even 
here  it  is  apt  to  exceed  the  limits  most  favour- 
able to  the  excitement  of  the  capillaries,  it  must 
generally  be  reduced ; and  in  proportion  as  we 
reduce  it,  we  find,  analogous  to  what  happens  in 
an  inflamed  part,  that  the  redness,  heat,  and  ful- 
ness of  the  various  surfaces  are  relieved.  It  is 
equally  necessary,  however,  both  in  fever  and  in- 
flammation, to  be  careful  that  we  do  not  so  far  re- 
duce the  vis  a tergo  that  it  Can  no  longer  support 
any  degree  of  circulation  in  the  debilitated  capil- 


286 


laries ; in  which  case  we  should  have  general 
sphacelus  in  fever,  as  we  have  local  sphacelus  in 
inflammation,  were  it  possible  that  any  of  the 
functions  of  life  could  go  on  after  all  the  capilla- 
ries had  lost  their  power.  In  extreme  cases  of 
typhus  we  see  a state  approaching  to  this. 

If  the  foregoing  observations  be  correct,  the 
treatment  of  fever  is  founded  on  the  same  princi- 
ples with  that  of  inflammation,  except,  that  as  the 
resisting  power  is  greater  in  fever,  less  vigorous 
means  of  reducing  the  vis  a tergo  are  proper  in 
the  early  stage  of  this  disease,  and  in  the  latter 
stage,  the  means  which  support  it  are  more  fre- 
quently called  for. 

The  attention  of  Mr.  Knight,  whose  discoveries 
in  the  vegetable  world  have  placed  him  in  the 
first  rank  of  philosophers,  has  been  peculiarly  at- 
tracted by  the  galvanic  experiments  which  have 
been  laid  before  the  reader ; and  the  strong  ana- 
logy which  subsists  between  animal  and  vegeta- 
ble life,  has  induced  him  to  reflect  much  on  their 
results.  He  has  favoured  me  with  many  inge- 
nious suggestions  relating  chiefly  to  vegetable  life, 
which  will  be  submitted  to  the  test  of  experiment. 
One  relating  to  the  subject  before  us,  I cannot 
avoid  mentioning,  although  I have  not  yet  had 
an  opportunity  of  attempting  to  profit  by  it.  I 
mean  the  use  of  galvanism  in  the  worst  cases  of 
typhus,  in  which  there  is  an  universal  failure  of 
the  secreting  power  and  the  debility  of  the  ner- 


287 

vous  system  forms  so  prominent  a feature.  It 
may  certainly  be  used  with  safety,  and  probably 
with  advantage  in  this  disease.  The  circum- 
stance which  appears  to  me  to  render  it  doubtful 
how  far  it  may  prove  useful  in  typhus  is,  that 
here  the  due  supply  of  fluids,  as  well  as  of  ner- 
vous influence,  fails.  In  restoring  the  former, 
galvanism  can  have  no  effect  different  from  that 
of  other  stimuli.  The  proper  mode  of  using  it,  I 
conceive  to  be,  by  many  wires  from  one  end  of  the 
trough  applied  to  various  parts  of  the  head  and 
spine,  and  many  from  the  other  end  applied  to 
such  parts  of  the  surface  as  shall  send  the  influ- 
ence through  the  body  as  much  as  possible  in  the 
direction  of  the  nerves.  Many  of  the  observa- 
tions which  I shall  have  occasion  to  make  on  the 
use  of  galvanism  in  asthma,  and  which  have  been 
confirmed  by  repeated  trials,  will  probably  be 
found  applicable  to  this  and  other  cases  in  which 
it  may  be  employed. 

Having  taken  a cursory  view  of  the  nature  of 
the  diseases  which  arise  from  morbid  distension, 
and  consequent  failure  of  circulation  in  the  ca- 
pillaries and  larger  vessels  of  the  brain,  we  are 
now  to  consider  the  effects  of  a deranged  state  of 
this  organ  itself,  and  how  far  the  experiments 
which  have  been  laid  before  the  reader  throw 
light  on  the  symptoms  arising  from  this  cause. 


288 


Of  Nervous  Apoplexy. 

It  is  still  one  of  the  great  desiderata  in  medi- 
cine to  discover  a diagnosis  between  sanguineous 
and  nervous  apoplexy.  The  objects  of  the  fol- 
lowing observations  are,  to  trace,  as  far  as  I can, 
with  the  aid  of  the  experiments  which  have  been 
laid  before  the  reader,  the  distinguishing  symp- 
toms of  nervous  apoplexy,  and  to  ascertain  the 
circumstances  which  render  the  diagnostic  be- 
tween this  disease  and  sanguineous  apoplexy  so 
difficult.  This  difficulty  is  much  to  be  lamented, 
as  there  is  no  instance  in  which  a diagnostic  is 
more  necessary,  these  diseases  often  proving 
quickly  fatal,  and  requiring  very  different  plans 
of  treatment. 

In  considering  this  subject,  I shall  in  the  first 
place  point  out  what  appears,  from  the  principles 
which  seem  to  be  established  by  the  experiments 
related  in  the  preceding  Inquiry,  to  be  the  neces- 
sary consequences  of  great  injury  of  the  brain  ; 
and  then  compare  these  consequences  with  the 
symptoms  which  actually  attend  diseased  states 
of  this  organ  in  the  human  body. 

As  it  appears,  as  far  as  I am  capable  of  judg- 
ing, from  what  has  been  said,  that  the  leading 
features  of  sanguineous  apoplexy  depend  on  the 
fact,  that  the  power  of  the  heart  and  blood  vessels 
is  independent  of  the  nervous  system,  in  conse- 


289 


quence  of  which  the  power  of  the  brain  may  be 
overwhelmed  by  a compressing  force,  without 
directly  affecting  the  powers  of  circulation  ;* * * §  so 
I think  it  will  appear  from  what  I am  about  to 
say,  that  the  leading  features  of  nervous  apo- 
plexy depend  on  the  fact,  that  the  power  of  the 
heart  and  blood  vessels,  though  independent  of 
the  nervous  system,  may  be  influenced  even  to  its 
total  destruction  through  this  system. f 

Let  us  consider  the  consequence  of  such  an  im- 
pression made  on  the  nervous  system  as  greatly 
lessens  the  power  of  the  heart  and  blood  vessels. 
We  have  seen  that  agents  acting  on  the  brain  and 
spinal  marrow  increase  the  action  of  the  heart  and 
blood  vessels,  unless  they  are  of  a sedative  qua- 
lity, or  applied  in  excess,  that  is,  in  such  a degree 
as  suddenly  to  injure  the  mechanism  of  the  brain 
and  spinal  marrow,  they  then  directly  impair  the 
powers  of  circulation.^  If  the  mechanism  of  the 
brain  be  suddenly  destroyed,  instant  death  of  all 
the  functions  ensues. § The  cause  applied,  how- 
ever, is  rarely  sufficient  to  produce  this  effect. 
It  generally  debilitates  without  destroying  the 
various  functions  5 the  sensibility  is  impaired ; 

* Exp.  1 8. 

t Compare  the  Experiments  related  in  Chap.  I.  of  this 
Part,  with  Exps.  19,  20,  21,  22,  26,  27,  29,  30. 

| See  the  Experiments  related  in  the  second  Chapter  of 
this  part. 

§ Exp.  20,  21. 

1?9 


290 


the  heart  acts  more  frequently  and  feebly,  and, 
for  the  most  part,  irregularly ; and  the  circulating 
system  suffers  a similar  loss  of  power  in  every 
part  of  the  body.  This  state  is  succeeded  by 
some  improvement  in  the  symptoms,  the  heart 
and  blood  vessels  in  some  degree  recover  from 
the  shock  they  received.*  The  former  begins 
to  beat  with  less  frequency  and  with  more  force 
and  regularity,  and  the  latter  to  convey  the  blood 
with  greater  velocity  and  in  a more  uniform 
stream.f  In  proportion  as  this  change  takes  place, 
the  various  functions,  as  I have  very  frequently  ob- 
served in  rabbits,  improve,  the  animal  recovering 
a greater  degree  of  sensibility.  If  the  offending 
cause  has  been  slight,  the  symptoms  continue  to 
improve ; if  severe,  the  heart  soon  begins  again 
to  beat  more  languidly,  and  with  it  all  the  func- 
tions gradually  fail.  If  the  injury  done  to  the 
nervous  system  is  of  such  a nature  as  particular- 
ly to  debilitate  the  vessels  of  the  injured  part, 
during  that  interval,  in  which  the  vigour  of  the 
circulation  is  in  some  degree  restored,  the  vessels 
of  this  part  must  yield  to  the  vis  a ter  go  and  the 
symptoms  of  inflammation  are  thus  added  to  those 
arising  from  the  original  injury. 

Such  appears  from  the  result  of  the  experiments 
detailed  in  the  preceding  Inquiry,  to  be  the  con- 


* Exp.  19,  29. 


t Ibid . 


29  i 


sequences  of  such  an  injury  of  the  brain  and  spi- 
nal marrow  as  materially  deranges  their  me- 
chanism. The  reader  will  perceive  that  if  the 
foregoing  view  of  the  subject  be  correct,  the  ner- 
vous is  a much  more  complicated  disease  than  the 
sanguineous  apoplexy.  In  the  latter,  the  powers 
of  the  nervous  system  are  oppressed,  but  those  of 
the  sanguiferous  system  are,  in  the  commence- 
ment of  the  disease,  entire,  and  only  become  af- 
fected through  the  failure  of  the  functions  of  respi- 
ration and  secretion.  In  nervous  apoplexy  the 
powers  of  circulation  not  only  suffer  directly  from 
the  injury  done  to  the  nervous  system,  thus  pro- 
ducing a combination  of  diseased  states  of  both 
systems,  but  the  debility  of  the  heart  and  blood 
vessels  have  a secondary  effect  on  the  nervous 
system.  The  action  of  the  brain  and  spinal  mar- 
row fail  from  defective  circulation,  and  a state  of 
these  organs,  analogous  to  that  which  takes  place 
in  syncope,  is  superadded  to  that  produced  by 
the  cause  of  the  disease.  It  is  not  surprising, 
therefore,  that  this  species  of  apoplexy  sometimes 
proves  instantly  fatal ; which  sanguineous  apo- 
plexy, affecting  the  powers  of  circulation  only, 
through  the  failure  of  other  functions.,  never  does. 

The  principles  of  the  treatment  in  the  former 
case  also,  are  much  more  complicated.  In  san- 
guineous apoplexy,  we  have  but  one  object  in 
view,  to  relieve  the  brain  from  pressure.  In 
nervous  apoplexy,  while  we  endeavour  to  coun- 


292 


teract  the  effects  of  the  offending  cause  on  the 
brain,  it  is  necessary  to  support  the  circulation; 
the  failure  of  which  to  a certain  degree  must  im- 
mediately prove  fatal.  This  ought  to  be  done, 
however,  in  such  a way  as  tends  least  to  occa- 
sion morbid  distension  of  the  vessels  of  the  head, 
to  which  the  cause  of  the  disease  often  renders 
them  liable,  and  which  will  produce  either  san- 
guineous apoplexy  or  plirenitis,  according  as  the 
distension  takes  place  in  the  larger  or  smaller 
vessels.  From  this  view  of  the  subject  we  may 
readily  understand  why  abstraction  of  blood  often 
proves  fatal  in  nervous  apoplexy,  and  yet  much 
stimulus  cannot  be  borne. 

The  simplest  cases  of  nervous  apoplexy,  and 
those  most  nearly  approaching  to  the  state  of  the 
animals  in  the  above  experiments,  are  cases  from 
mechanical  injury  of  the  brain.  When  a blow  on 
the  head  fractures  the  scull  and  occasions  part  of 
the  bone  to  press  on  the  brain  without  doing  fur- 
ther injury  to  this  organ,  the  case  resembles  in 
its  nature  the  sanguineous  apoplexy.  When  the 
compressing  power  is  removed,  the  apoplectic 
symptoms  disappear;  but  when  the  blow  has 
produced  what  surgeons  call  concussion  of  the 
brain,  the  case  is  only  a slighter  degree  of  the 
state  in  which  the  rabbits  and  frogs  were  found 
after  the  brain  had  been  crushed. 

No  writer,  perhaps,  has  detailed  the  symptoms 
of  concussion  of  the  brain  with  greater  correctness 


293 


than  Mr.  Abernethy,  in  the  third  part  of  his  Sur- 
gical and  Physiological  Essays.  It  is  impossible 
not  to  remark  how  accurately  his  account  of  these 
symptoms  corresponds  with  the  results  of  the 
experiments  which  have  been  laid  before  the 
reader : — e<  The  whole  train  of  symptoms,”  he 
observes,  u following  a concussion  of  the  brain, 
may,  I think,  be  properly  divided  into  three 
stages.  The  first  is,  that  state  of  insensibility 
and  derangement  of  the  bodily  powers  which  im- 
mediately succeed  the  accident.  While  it  lasts, 
the  patient  scarcely  feels  any  injury  that  may  be 
inflicted  on  him ; his  breathing  is  difficult,  but  in 
general  without  stertor;  his  pulse  intermitting, 
and  his  extremities  cold.  But  such  a state  can- 
not last  long;  it  goes  off  gradually,  and  is  suc- 
ceeded by  another,  which  I consider  as  the  second 
stage  of  concussion.  In  this,  the  pulse  and  respi- 
ration become  better,  and,  though  not  regularly 
performed,  are  sufficient  to  maintain  life,  and  to 
diffuse  warmth  over  the  extreme  parts  of  the 
body.  The  feeling  of  the  patient  is  now  so  far 
restored  that  he  is  sensible  if  his  skin  is  pricked, 
but  he  lies  stupid  and  inattentive  to  slight  exter- 
nal impressions.  As  the  effects  of  concussion 
diminish,  he  becomes  capable  of  replying  to  ques- 
tions put  to  him  in  a loud  tone  of  voice,  especially 
when  they  refer  to  his  chief  suffering  at  the  time, 
as  pain  in  the  head,  &c. ; otherwise  he  answers 
incoherently,  and  as  if  his  attention  was  occupied 


291 


by  something  else.  As  long  as  the  stupor  re- 
mains, the  inflammation  of  the  brain  seems  to  be 
moderate,  but  as  the  former  abates,  the  latter 
seldom  fails  to  increase ; and  this  constitutes  the 
third  stage  which  is  the  most  important  of  the  se- 
ries of  effects  proceeding  from  concussion.  These 
several  stages  vary  considerably  in  their  degree 
and  duration,  but  more  or  less  of  each  will  be 
found  to  take  place  in  every  instance  where  the 
brain  has  been  violently  shaken.”  Page  59,  60. 
In  the  67th  page  Mr.  Abernethy  observes — li  It 
has  hitherto  been  considered  as  a desirable  object 
to  point  out  any  marks  by  which  we  might  dis- 
tinguish between  compression  and  concussion  of 
the  brain,  but  I believe  no  such  criteria  have  yet 
been  communicated  to  the  public.  I think,  how- 
ever, that  these  diseases  may  be  distinguished. 
As  far  as  my  observation  goes,  the  insensibility  is 
much  less  in  concussion,  especially  after  a short 
time  has  elapsed.  Patients,  in  this  case,  though 
they  seem  reluctant  to  answer  questions,  yet  com- 
plain much  if  their  heads  are  moved,  and  in  those 
instances  where  it  was  judged  necessary  to  in- 
spect the  bone,  I have  generally  found  that  they 
made  great  complaint  during  the  operation.  The 
pupils  also  are  usually  more  contracted  than  in 
compression  of  the  brain,  the  muscles  of  the  limbs 
retain  their  natural  state  of  tone,  and  respiration 
is  performed  with  little  or  no  stertor,  though  the 
pulse  generally  intermits  in  a very  considerable 


295 


degree.  In  the  slighter  cases  of  concussion  the 
sickness  of  the  patient  is  often  very  great.  But 
in  cases  of  compression  of  the  brain  circumstances 
very  much  the  reverse  of  those  just  related  take 
place.  The  sensibility  is  much  diminished  in 
proportion  to  the  degree  of  the  injury.  From 
this  cause  also  the  pupils  are  dilated  and  the 
limbs  relaxed.  The  respiration  is  attended  Avith 
stertor,  and  the  pulse,  as  far  as  my  observation 
extends,  is  subject  to  much  less  intermission.” 
It  is  evident  that  in  accidents  Ave  cannot  always 
expect  to  find  the  symptoms  of  compression  and 
concussion  so  distinct  as  in  experiments  made  for 
the  purpose  of  exhibiting  those  symptoms ; many 
accidents  tending  at  the  same  time  to  produce  a 
greater  or  less  degree  of  both  affections. 

The  chief  difference  between  the  symptoms  of 
concussion  and  nervous  apoplexy  arising  from  in- 
ternal causes  is,  that  in  the  latter  there  is  not  so 
uniform  a tendency  to  inflammation,  Avhich  in  the 
cases  referred  to  by  Mr.  Abernethy  is  evidently 
the  effect  of  the  injury  done  to  the  vessels  by  the 
bloAV,  Avhich  Ave  have  reason  to  believe  causes 
them  to  suffer  morbid  distension  as  soon  as  a cer- 
tain vigour  of  circulation  is  restored.  It  is  this 
renewed  vigour  of  circulation  after  the  immediate 
effect  of  the  blow  has  subsided,  so  remarkable  in 
the  experiments  just  referred  to,  that  again  gives 
some  energy  to  the  brain,  and  explains  Mr.  Aber- 


296 


nethy’s  observation,  that  the  stupor  abates  as  the 
tendency  to  inflammation  comes  on. 

In  nervous  apoplexy,  from  internal  causes,  the 
sensibility  is  often  as  much  impaired  as  in  the 
sanguineous  apoplexy.  When  this  is  the  case 
the  danger  is  very  urgent ; hut  it  frequently  is 
much  less  so,  compared  with  the  severity  of  the 
other  symptoms  and  the  degree  of  danger,  than 
in  the  latter  species  of  the  disease ; because  here 
the  sanguiferous,  as  well  as  the  nervous  system, 
suffers.  In  the  former  case,  the  derangement  of 
function  being  confined  to  the  nervous  system, 
the  danger  is  nearly  proportioned  to  the  degree 
of  insensibility  ; hut  in  the  case  before  us,  symp- 
toms of  the  greatest  danger  often  occur,  although 
the  patient  is  not  wholly  insensible,  and  not  un- 
frequently  while  he  is  affected  with  a degree  of 
irritability.  The  state  of  the  pulse  affords  the 
best  diagnostic  between  these  species  of  apoplexy. 
In  the  sanguineous,  we  have  seen,  it  is  strong, 
regular,  and  generally  less  frequent  than  natural ; 
in  the  nervous,  it  is  weak,  frequent,  irregular, 
and  sometimes  fluttering. 

Such  are  the  symptoms  of  distinctly  formed 
sanguineous  and  nervous  apoplexy.  Were  these 
diseases  always  so  formed,  no  attentive  practi- 
tioner could  be  at  a loss  to  distinguish  them.  But 
we  have  to  lament  that  this  is  by  no  means  the 
case,  as  indeed  from  what  has  been  said  we  might 


297 


a priori  have  supposed.  For  it  must  often  hap- 
pen in  apoplexy  from  distension  of  the  vessels, 
that  the  brain  will  sustain  some  further  injury 
than  that  of  mere  uniform  compression.  It  is  not 
improbable  that  the  circumstance  of  the  compres- 
sing force  acting  partially,  may  sometimes  alone 
be  sufficient  to  produce  this  effect ; and  powerful 
causes,  injuring  the  mechanism  of  the  brain,  must 
often  be  of  such  a nature  as  at  the  same  time  to 
occasion  debility,  and  consequently  more  or  less 
distension  of  its  vessels.  To  these  circumstances, 
and  to  the  difficulty  of  distinguishing  apoplexy 
arising  from  mere  distension  of  the  vessels,  from 
that  arising  from  an  extravasation  of  blood  or 
serum,  it  appears  to  me  that  all  the  difficulties  of 
the  prognosis  and  diagnosis  of  the  different  spe- 
cies of  this  disease  are  to  be  ascribed. 

It  is  the  tendency  to  distension  of  the  vessels  of 
the  encephalon  that  renders  a very  stimulating 
plan  of  treatment  a doubtful  practice,  even  in  the 
most  decided  cases  of  nervous  apoplexy.  Were 
it  not  for  this,  the  state  of  the  sanguiferous  and 
nervous  systems  in  these  cases  equally  calls  for 
such  a plan.  But  it  would  seem  that  the  more 
debilitated  the  brain  is,  the  more  readily  it  feels 
the  effects  of  any  morbid  distension  of  its  vessels. 
Thus  our  practice  in  such  cases  is  confined  on  all 
hands.  Irreparable  injury  may  be  done  by  the 
free  use  either  of  stimuli  or  evacuants.  The 

mode  of  treatment  which  has  appeared  to  me  the 

40 


298 


most  successful,  is  a gently  stimulating  plan  com- 
bined, for  the  purpose  of  preventing  congestion 
of  the  head,  with  medicines  moderately  determin- 
ing to  the  surface,  and  keeping  the  bowels  free 
without  occasioning  a great  discharge  from  them  ; 
with  occasional  abstractions  of  blood  from  the 
head,  when  the  insensibility  seems  inclined  to  in- 
crease. Profuse  sweating  not  relieving  the  symp- 
toms, which  is  a frequent  occurrence  in  severe 
cases  of  nervous  apoplexy,  seems  always  to  indi- 
cate great  danger,  and  to  arise  from  a general  re- 
laxation of  the  extreme  vessels.  In  cases  arising 
from  injuries  of  the  head,  Mr.  Abernethy  thinks 
the  great  tendency  to  inflammation  altogether  for- 
bids the  stimulating  plan.  I have  already  pointed 
out  the  circumstance  which  often  makes  the  indi- 
cations of  cure  in  this  respect  different  in  concus- 
sion of  the  brain  and  nervous  apoplexy  arising 
from  internal  causes. 

The  foregoing  view  of  the  nature  of  the  diffe- 
rent species  of  apoplexy,  not  the  result  of  precon- 
ceived opinions,  but  of  facts  open  to  the  exami- 
nation of  every  one  who  chooses  to  repeat  the  ex- 
periments, and  so  strikingly  confirmed  by  the  ob- 
servations of  Mr.  Abernethy  and  other  writers  on 
the  effects  of  injuries  of  the  brain,  may  tend  per- 
haps to  render  the  practice  in  this  varied  disease 
more  determinate.  It  seems,  by  affording  a more 
correct  view  of  the  ratio  symptomatum  of  the  san- 
guineous and  nervous  apoplexy,  than  could  be  ob- 


299 


tained  without  a knowledge  of  the  relation  which 
subsists  between  the  sanguiferous  and  nervous 
systems,  to  point  out  with  more  precision  than 
has  yet  been  done,  the  symptoms  essential  to  each, 
and  consequently  the  modes  of  practice  suited  to 
the  various  cases  in  which  they  occur  separately, 
or  are  blended  together.  I have  entered  no  fur- 
ther on  these  modes  of  practice  than  was  necessary 
to  point  out  the  general  principles  on  which  they 
seem  to  be  founded. 

Of  Affections  of  the  Spinal  Marrow. 

The  experiments  in  which  different  portions  of 
the  spinal  marrow  were  destroyed*  seem  to  throw 
considerable  light  on  the  nature  of  the  symptoms 
occasioned  by  diseases  of  this  organ.  We  have 
seen  that  the  destruction  of  any  part  of  it  not  only 
renders  paralytic,  that  is,  deprives  of  their  only 
stimulus,  the  muscles  of  voluntary  motion  which 
correspond  to  that  part,  and  to  all  parts  of  the  spi- 
nal marrow  lying  below  it ; but,  by  lessening  the 
supply  of  nervous  influence  to  the  great  chain  of 
ganglions,  influences  the  state  of  the  thoracic  and 
abdominal  viscera  and  the  temperature  of  the  ani- 
mal. f In  estimating  the  effect  on  the  thoracic 

* Exp.  58,  59,  60. 

t It  appears  from  what  has  been  said,  that  although  both 
the  muscles  corresponding  to  the  part  of  the  spinal  marrow 


300 


and  abdominal  viscera  of  destroying  portions  of 
the  spinal  marrow,  we  must  trust  rather  to  the 
appearances  observed  in  the  lungs  and  stomach 
after  death  than  to  the  symptoms  produced,  be- 
cause, as  the  animal  can  give  no  account  of  its  feel- 
ings, no  symptom  of  deranged  digestion  appears 
till  it  goes  so  far  as  to  produce  efforts  to  vomit, 
nor  of  oppressed  breathing  till  it  goes  so  far  as 
to  produce  evident  dyspnoea.  Thus,  in  the  expe- 
riments just  referred  to,  it  appeared  on  dissection, 
that  the  process  of  digestion  was  sometimes  wholly 
suspended,  and  the  lungs  more  or  less  congested, 
where  no  symptoms  of  indigestion,  and  little  or 
no  change  in  the  breathing,  had  been  observed. 
We  often  complain  of  affections  of  the  stomach 
and  lungs  long  before  their  symptoms  can  be  per- 
ceived by  others.  Congestion  and  even  inflam- 
mation of  the  lungs  do  not  excite  cough  in  the 
rabbit. 

Even  in  early  stages  of  diseased  spine,  affec- 
tions of  the  stomach  and  lungs  frequently  attend, 
and  the  patient  often  complains  of  a sense  of  cold. 
Mr.  Pott  remarks  of  this  disease,  “ loss  of  appe- 
tite, a hard  dry  cough,  laborious  respiration,  &c. 
appear  pretty  early,  and  in  such  a manner  as  to 

destroyed,  and  those  corresponding  to  all  parts  below  it, 
equally  cease  to  move,  it  is  from  different  causes ; the  former 
because  their  nervous  influence  is  destroyed ; the  latter  be- 
cause their  nervous  influence  is  no  longer  subject  to  the  sen- 
sorium. 


801 


demand  attention.”  And  in  another  place  he  ob- 
serves, that  there  is  “ an  unusual  sense  of  cold- 
ness of  the  thighs,  not  accountable  for  from  the 
weather.”  Similar  observations  are  made  by  every 
writer  on  diseased  spine.  From  what  I shall 
have  occasion  to  say  of  asthma  and  dyspepsia  the 
reader  will  see  reas  on  to  believe  that  the  forego- 
ing symptoms  may  probably  be  relieved  from  time 
to  time  by  the  use  of  galvanism. 

It  appears  from  experiment  63,  in  which  the  spi- 
nal marrow  was  simply  divided,  compared  with 
experiments  58,  59,  60,  in  which  portions  of  it 
were  destroyed,  that  we  may  judge  of  the  extent 
of  the  injury  done  to  this  organ,  in  diseases  of  the 
spine,  by  the  state  of  the  stomach  and  lungs. 
Any  thing,  which  so  affects  the  spinal  marrow 
as  to  interrupt  the  communication  between  the 
brain  and  other  parts,  will  of  course  prevent  the 
influence  of  the  will  reaching  them,  however 
small  a part  of  the  spinal  marrow  may  be  injured. 
But  if  a considerable  part  of  it  is  so,  along  with 
loss  of  power  in  the  limbs,  the  patient  will  expe- 
rience symptoms  of  dyspepsia  and  oppressed 
breathing  proportioned  to  the  importance  and  ex- 
tent of  the  part  whose  function  is  destroyed.  I 
have  already  had  occasion  to  explain  why  the 
lungs  are  particularly  affected  by  the  destruction 
of  the  dorsal,  and  the  intestines  by  that  of  the  lum- 
bar portion  of  the  spinal  marrow.* 

* Page  188  et.  seq. 


302 


The  experiments  related  in  the  preceding  in- 
quiry seem  to  point  out  more  precisely  than  for- 
mer observations  have  done,  what  we  are  to  ex- 
pect from  the  use  of  galvanism  in  the  cure  of  dis- 
ease ; and  I think  it  will  appear  from  what  I am 
about  to  say,  that  to  the  want  of  discrimination 
in  its  employment  we  must  ascribe  the  little  ad- 
vantage which  medicine  has  hitherto  derived  from 
the  discovery  of  this  influence.* 

It  seems  to  be  an  inference  from  my  own  ex- 
periments and  observations, f as  well  as  those  of 
others,  particularly  of  M.  le  Grallois,  that  what  is 
called  the  nervous  system,  comprehends  two  dis- 
tinct systems,  the  sensorial,  and  the  nervous  sys- 
tem properly  so  called.  Now,  it  does  not  appear 
that  galvanism  can  perform  any  of  the  functions 
of  the  sensorial  system,  yet,  in  the  greater  number 
of  instances  in  which  it  has  been  used  in  medi- 
cine, it  has  been  expected  to  restore  the  sensorial 
power.  It  has  been  expected  to  restore  hearing, 
and  sight,  and  voluntary  power.  It  may  now 
and  then  happen  in  favourable  cases,  from  the 
connection  which  subsists  between  the  sensorial 
and  nervous  systems,  that  by  rousing  the  energy 

* Many  of  the  following  observations  on  Galvanism  are 
re-publishecl  from  a paper  which  the  Royal  Society  did  me 
the  honour  of  publishing  in  the  Philosophical  Transactions 
of  this  year. 

t See  Chap.  10,  and  the  experiments  there  referred  to. 


303 


of  the  latter,  we  may  excite  the  former.  It  would 
be  easy  to  shew,  that  we  have  little  reason  to  ex- 
pect that  this  will  often  happen.  We  have  also 
reason  to  believe  from  the  experiments  which 
have  been  laid  before  the  reader,  that  galvanism 
has  no  other  power  over  the  muscular  system, 
than  that  of  a stimulus  ;*  we  are,  therefore  to  ex- 
pect little  more  advantage  from  it  in  diseases  de- 
pending wholly  on  faults  of  the  sanguiferous  sys- 
tem, than  from  other  stimuli.  Hence  its  failure 
in  tumors,  &c.  But  I cannot  help  regarding  it  as 
almost  ascertained,  that  in  those  diseases  in  which 
the  derangement  is  in  the  nervous  power  alone, 
where  the  sensorial  functions  are  entire,  and  the 
vessels  healthy,  and  merely  the  power  of  secre- 
tion, which  seems  immediately  to  depend  on  the 
nervous  system,  is  in  fault,  galvanism  will  often 
prove  a valuable  means  of  relief. 

Of  Asthma  and  Dyspepsia. 

As  soon  as  the  foregoing  view  of  the  subject 
presented  itself,  I was  led  to  inquire,  what  dis- 
eases depend  on  a failure  of  nervous  influence. 
The  effect  on  the  stomach  and  lungs,  of  divid- 
ing the  eighth  pair  of  nerves, f answered  the 

* Compare  the  experiments  related  in  the  first  and  second 
Chapters  of  this  part  of  the  Inquiry  with  Exp.  46, 47. 48, 49. 
and  the  observations  which  follow  them. 

t Exp.  44,  45. 


304 


question  respecting  two  of  the  most  important 
diseases  of  this  class.  We  have  seen  that  with- 
drawing a considerable  part  of  the  nervous  in- 
fluence from  the  stomach  and  lungs  deranges  the 
digestive  powers,  and  produces  great  difficulty  of 
breathing.  The  following  observations  relate 
chiefly  to  affections  of  the  lungs.  Of  the  effects 
of  galvanism  in  dyspepsia,  the  principal  experi- 
ence which  I have  yet  had,  has  been  in  cases 
where  it  was  complicated  with  asthmatic  breath- 
ing. 

When  the  effect  of  depriving  the  lungs  of  a con- 
siderable part  of  their  nervous  influence  is  care- 
fully attended  to,  it  will  be  found,  I think,  in  all 
respects  similar  to  a common  disease,  which  may 
be  called  habitual  asthma,  in  which  the  breath- 
ing is  constantly  oppressed,  better  and  worse  at 
different  times,  but  never  free,  and  often  continues 
to  get  worse,  in  defiance  of  every  means  we  can 
employ,  till  the  patient  is  permanently  unfitted 
for  all  the  active  duties  of  life.  The  animal,  in 
the  above  experiment,  is  not  affected  with  the 
croaking  noise  and  violent  agitation  which  gene- 
rally characterise  fits  of  spasmodic  asthma.  This 
state  we  cannot  induce  artificially,  except  by 
means  which  lessen  the  aperture  of  the  glottis. 

We  have  seen,  from  repeated  trials,  that  both 
the  oppressed  breathing  and  the  collection  of 
phlegm,  caused  by  the  division  of  the  eighth  pair 
of  nerves,  may  be  prevented  by  sending  a stream 


305 


of  galvanism  through  the  lungs.*  That  this  may 
be  done  with  safety  in  the  human  body  we  know 
from  numberless  instances,  in  which  galvanism 
has  been  applied  to  it  in  every  possible  way. 

Such  are  the  circumstances  which  led  me  to 
expect  relief  from  galvanism  in  habitual  asthma. 
It  is  because  that  expectation  has  not  been  dis- 
appointed, that  I trouble  the  reader  with  the  fol- 
lowing account  of  its  effects.  Although  the  effects 
of  galvanism  in  habitual  asthma  have  been  wit- 
nessed by  many  other  medical  men,  I have  men- 
tioned nothing  in  the  following  pages  which  did 
not  come  under  my  own  observation. 

I have  employed  galvanism  in  many  cases  of 
habitual  asthma,  and  almost  uniformly  with  relief. 
The  time,  during  which  the  galvanism  was  ap- 
plied, before  the  patient  said  that  his  breathing 
was  easy,  has  varied  from  five  minutes  to  a quar- 
ter of  an  hour.  I speak  of  its  application  in  as 
great  a degree  as  the  patient  could  bear  without 
complaint.  For  this  effect  I generally  found 
from  eight  to  sixteen  four-inch  plates  of  zinc  and 
copper,  the  fluid  employed  being  one  part  of  mu- 
riatic acid,  and  twenty  of  water,  sufficient.  Some 
require  more  than  sixteen  plates,  and  a few  can- 
not bear  so  many  as  eight : for  the  sensibility  of 
different  individuals  to  galvanism  is  very  differ- 
ent. It  is  curious,  and  not  easily  accounted  for, 

* Exp.  46,  47,  48,  4?. 

41 


306 


that  a considerable  power,  that  perhaps  of  twenty- 
five  or  thirty  plates  is  often  necessary  on  first 
applying  the  galvanism,  in  order  to  excite  any 
sensation  ; yet  after  the  sensation  is  once  excited, 
the  patient  shall  not  perhaps,  particularly  at  first, 
be  able  to  bear  more  than  six  or  eight  plates. 
The  stronger  the  sensation  excited,  the  more 
speedy  in  general  is  the  relief.  I have  known 
the  breathing  instantly  relieved  by  a very  strong 
power.  I have  generally  made  it  a rule  to  begin 
with  a very  weak  one,  increasing  it  gradually  at 
the  patient’s  request,  by  moving  one  of  the  wires 
from  one  division  of  the  trough  to  another,  and 
moving  it  back  again  when  he  complained  of  the 
sensation  being  too  strong.  It  is  convenient  for 
this  purpose  to  charge  with  the  fluid  about  thirty 
plates. 

The  galvanism  was  applied  in  the  following 
manner.  Two  thin  plates  of  metal  about  two  or 
three  inches  in  diameter,  dipped  in  water,  were 
applied,  one  to  the  nape  of  the  neck,  the  other  to 
the  pit  of  the  stomach,  or  rather  lower.  The 
wires  from  the  different  ends  of  the  trough*  were 
brought  into  contact  with  these  plates,  and,  as 
observed  above,  as  great  a galvanic  power  main- 
tained, as  the  patient  could  bear  without  com- 
plaint. In  this  Avay  the  galvanic  influence  was 

* I found  a trough  of  the  old  construction  answer  better 
than  the  improved  pile,  which  is  so  much  superior  for  most 
purposes. 


307 


sent  through  the  lungs,  as  much  as  possible,  in  the 
direction  of  their  nerves.  It  is  proper,  constantly 
to  move  the  wires  upon  the  metal  plates,  particu- 
larly the  negative  wire,  otherwise  the  cuticle  is 
injured  in  the  places  on  which  they  rest.  The 
relief  seemed  much  the  same,  whether  the  posi- 
tive wire  was  applied  to  the  nape  of  the  neck,  or 
the  pit  of  the  stomach.  The  negative  wire  gene- 
rally excites  the  strongest  sensation.  Some  pa- 
tients thought,  that  the  relief  was  most  speedy, 
when  it  was  applied  near  the  pit  of  the  stomach. 

The  galvanism  was  discontinued  as  soon  as 
the  patient  said  that  his  breathing  was  easy.  In 
the  first  cases  in  which  I used  it,  I sometimes  pro- 
longed its  application  for  a quarter  of  an  hour, 
or  twenty  minutes,  after  the  patient  said  he  was 
perfectly  relieved,  in  the  hope  of  preventing  the 
early  recurrence  of  the  dyspnoea  y but  I did  not 
find  that  it  had  this  effect.  It  is  remarkable,  that  in 
several  who  had  laboured  under  asthmatic  breath- 
ing for  from  ten  to  twenty  years,  it  gave  relief 
quite  as  readily  as  in  more  recent  cases  ; which 
proves,  that  the  habitual  difficulty  of  breathing, 
even  in  the  most  protracted  cases,  is  not  to  be 
ascribed  to  any  permanent  change  having  taken 
place  in  the  lungs. 

With  regard  to  that  form  of  asthma  which  re- 
turns in  violent  paroxysms,  with  intervals  of  per- 
fectly free  breathing,  I should  expect  little  advan- 
tage from  galvanism  in  it,  because,  as  I have  just 


308 


observed,  I found  that  the  peculiar  difficulty  of 
breathing,  which  occurs  in  this  species  of  asthma, 
cannot  be  induced  in  animals,  except  by  means 
lessening  the  aperture  of  the  glottis.  It  is  pro- 
bable, that  in  the  human  subject  the  cause  pro- 
ducing this  effect  is  spasm,  from  which  indeed 
the  disease  takes  its  name,  and  we  have  no  rea- 
son to  believe,  from  what  we  know  of  the  nature 
of  galvanism,  that  it  will  be  found  the  means  of 
relaxing  spasm. 

The  spasmodic  asthma  is,  fortunately,  a very 
rare  disease,  so  much  so,  that  but  one  case  of  it 
has  occured  to  me  since  I have  employed  galvan- 
ism in  asthma,  while  I have  had  au  opportunity 
of  employing  this  remedy  in  about  forty  cases  of 
the  habitual  form  of  the  disease.  I cannot,  there- 
fore, from  experience,  speak  with  certainty  of  the 
effect  of  galvanism  in  the  former.  In  the  above 
case  it  was  twice  employed  in  the  paroxysm,  and 
I could  observe  no  relief  from  it.  In  both  in- 
stances, the  patient  said  that,  had  it  not  been  used, 
the  symptoms  would  have  been  more  severe.  In 
this  patient,  the  spasmodic  paroxysm  was  often 
succeeded  by  a state  of  habitual  asthma  for  seve- 
ral weeks,  in  which  galvanism  gave  immediate, 
but  temporary  relief. 

Of  the  above  cases  of  habitual  asthma,  many 
occurred  in  work-people  of  the  town  where  I re- 
side, who  had  been  obliged  to  abandon  their  em- 
ployments in  consequence  of  it,  and  some  of  them. 


309 


from  its  long  continuance,  without  any  hope  of 
returning  to  regular  work.  Most  of  them  had 
tried  the  usual  means  in  vain.  By  the  use  of 
galvanism  they  were  relieved  in  different  degrees, 
but  all  sufficiently  to  be  restored  to  their  employ- 
ments. I have  seen  several  of  them  lately,  who, 
although  they  have  not  used  the  galvanism  for 
some  months,  said  they  had  continued  to  work 
without  any  inconvenience.  Some,  in  whom  the 
disease  had  been  wholly  removed,  remain  quite 
free  from  it ; some  have  had  a return  of  it,  and 
have  derived  the  same  advantage  from  the  gal- 
vanism as  at  first. 

I have  confined  the  application  of  galvanism 
to  asthmatic  dyspnoea.  I think  there  is  reason 
to  believe,  from  the  experiments  which  have  been 
laid  before  the  reader,  that  in  inflammatory  cases 
it  would  be  injurious,  and,  in  cases  arising  from 
dropsy,  or  any  other  mechanical  impediment, 
little  or  nothing,  it  is  evident,  is  to  be  expected 
from  it.  Habitual  asthma  is  often  attended  with 
a languid  state  of  the  biliary  system,  and  some 
fullness  and  tenderness  on  pressure  near  the  pit 
of  the  stomach.  If  the  last  is  considerable,  it 
must  be  relieved  previous  to  the  use  of  the  gal- 
vanism. In  a paper  which  the  Medico- Chirurgi- 
cal  Society  did  me  the  honour  to  publish  in  the 
seventh  volume  of  their  Transactions,  I have  en- 
deavoured to  shew  that  a species  of  pulmonary 
consumption  arises  from  a disease  of  the  digestive 


310 


organs.  Many  of  the  observations  there  made 
apply  to  certain  cases  of  asthma  I believe  to 
cases  of  every  species  of  this  disease,  but  parti- 
cularly of  that  we  are  here  considering.  Many 
cases  of  habitual  asthma  will  yield  to  the  means 
recommended  in  the  above  paper,  but  I have 
learned,.,  from  a pretty  extensive  experience,  that 
a large  majority  of  such  cases  will  resist  them, 
yet  readily  admit  of  relief  from  galvanism.  If 
there  is  little  tendency  to  inflammation,  galvanism 
seems  also  to  be  a means  of  relieving  the  affection 
of  the  digestive  organs.  I have  repeatedly  seen 
from  it  the  same  effect  on  the  biliary  system  which 
arises  from  calomel ; a copious  bilious  discharge 
from  the  bowels  coming  on  within  a few  hours 
after  its  employment.  This  seldom  happens  ex- 
cept where  there  appears  to  have  been  a failure 
in  the  secreting  power  of  the  liver,  or  a defective 
action  in  the  gall  tubes. 

I have  not  found  that  the  presence  even  of  a se- 
vere cough,  which  is  common  in  habitual  asthma, 
in  which  there  is  always  more  or  less  cough,  couu- 
ter-indicates  the  use  of  galvanism.  The  cough 
under  its  use  generally  becomes  less  frequent  in 
proportion  as  the  accumulation  of  phlegm  in  the 
lungs  is  prevented ; but  it  seems  to  have  no  direct 
effect  in  allaying  it.  In  some  cases  the  cough  coii- 

* See  the  observations  on  the  state  of  these  organs  in  asth- 
ma, in  Dr.  Bree’s  work  on  this  disease. 


311 


tiuued  troublesome  after  the  dyspnoea  had  disap- 
peared. Galvanism  never  appeared  to  increase 
it,  except  when  the  inflammatory  diathesis  was 
considerable.  In  some  labouring  under  the  most 
chronic  forms  of  phthisis,  in  whom  the  symptoms 
had  lasted  several  years  and  habitual  asthma  had 
supervened,  the  relief  obtained  from  galvanism 
was  very  great,  notwithstanding  some  admixture 
of  a pus-like  substance  in  what  was  expectorated. 
I need  hardly  add,  after  what  has  been  said,  that 
in  ordinary  cases  of  phthisis  nothing  could  be 
more  improper  than  the  ase  of  galvanism.  The 
dyspnoea  arising  from  phthisis  and  that  from  ha- 
bitual asthma  are  easily  distinguished.  The  for- 
mer is  less  variable.  It  is  generally  increased  by 
the  exacerbations  of  the  fever,  and  always  by  ex- 
ercise. When  the  patient  is  still  and  cool,  except 
in  the  last  stages  of  phthisis,  his  breathing  is  ge- 
nerally pretty  easy.  The  latter  is  worst  at  par- 
ticular times  of  the  day,  and  frequently  becomes 
better  and  worse  without  any  evident  cause.  At 
the  times  when  it  is  better  the  patient  can  often 
use  exercise  without  materially  increasing  it. 
Changes  of  the  weather  influence  it  much.  It  is 
particularly  apt  to  be  increased  by  close  and  foggy 
weather.  Phthisical  dyspnoea  is  seldom  much 
influ enced  by  changes  of  the  w-eather,  except  they 
increase  the  inflammatory  tendency. 

When  there  is  a considerable  tendency  to  in- 
flammation in  habitual  asthma,  the  repeated  ap- 


312 


plication  of  galvanism  sometimes  increases  it  so 
much,  that  the  use  of  this  influence  no  longer 
gives  relief,  till  the  inflammatory  tendency  is  sub- 
dued by  local  blood-letting.  It  always  gave  relief 
most  readily,  and  the  relief  was  generally  most 
permanent,  in  those  cases  which  were  least  com- 
plicated with  other  diseases,  the  chief  complaint 
being  a sense  of  tightness  across  the  region  of 
the  stomach,  impeding  the  breathing.  The  pa- 
tients said,  that  the  sense  of  tightness  gradually 
abated  while  they  were  under  the  influence  of  the 
galvanism,  and  that  as  this  happened  their  breath- 
ing became  free.  The  abatement  of  the  tightness 
was  often  attended  with  a sense  of  warmth  in  the 
stomach,  which  seemed  to  come  in  its  place.  This 
sensation  was  most  frequently  felt  when  the  nega- 
tive wire  was  applied  near  the  pit  of  the  stomach, 
but  the  relief  did  not  seem  less  when  it  was  not 
felt. 

With  respect  to  the  continuance  of  the  relief 
obtained  by  galvanism,  it  was  different  in  differ- 
ent cases ; in  the  most  severe  cases  it  did  not  last 
so  long  as  in  those  where  the  symptoms  were 
slighter,  though  of  equal  continuance.  This 
observation,  however,  did  not  universally  apply. 
When  the  patient  was  galvanised  in  the  morning, 
he  generally  felt  its  good  effects  more  or  less  till 
next  morning.  In  almost  all,  the  repetition  of 
the  galvanism  gradually  increased  the  degree  of 
permanent  relief.  Its  increase  was  much  more 


313 


rapid  in  some  cases  than  in  others.  The  per- 
manency of  the  good  effects  of  galvanism  in  the 
disease  before  us,  has  appeared  very  remarkably 
in  several  cases  where  the  symptoms,  after  hav- 
ing been  removed  by  it,  were  renewed  after  in- 
tervals of  different  duration  by  cold  or  other 
causes.  In  these  cases  means  which,  previous 
to  the  use  of  galvanism,  had  failed  to  give  relief, 
were  now  successful  without  its  aid;  or  with  few 
applications  of  it,  compared  with  those  which  had 
been  necessary  in  the  first  instance.  I have  not 
yet  seen  any  case,  in  which  galvanism  had  been 
of  considerable  advantage,  where  its  good  effects 
appeared  to  have  been  wholly  lost.  It  is  now 
about  a year  and  a half  since  I first  employed  it 
in  habitual  asthma.  Taking  cold,  and  the  ex- 
cessive use  of  fermented  liquors  have  been  the 
principal  causes  of  relapse. 

The  galvanism  was  seldom  used  more  than 
once  a day.  In  some  of  the  more  severe  cases  it 
was  used  morning  and  evening.  About  a sixth 
part  of  those  who  have  used  it  appear,  as  far  as 
we  yet  know,  to  have  obtained  a radical  cure. 
It  in  no  case  failed  to  give  more  or  less  relief, 
provided  there  was  little  inflammatory  tendency. 
It  failed  to  give  considerable  relief  only  in  about 
one-tenth ; I may  add,  that  were  it  only  the  means 
of  present  relief,  we  have  reason  to  believe  that, 
as  being  more  innocent,  it  would  be  found  pre- 
ferable to  the  heating,  spirituous,  and  soporific 

42 


314 


medicines,  which  are  so  constantly  employed  in 
this  disease. 

As  it  often  happened  that  a very  small  gal- 
vanic power,  that  of  not  more  than  from  four  to  six 
four-inch  double  plates,  relieved  the  dyspnoea, 
may  we  not  hope,  that  a galvanic  apparatus  may 
be  constructed,  which  can  be  worn  by  the  patient, 
of  sufficient  power  to  prevent  its  recurrence  in 
some  of  the  cases  in  which  the  occasional  use  of 
the  remedy  does  not  produce  a radical  cure  ? 

I wished  to  try,  if  the  impression  on  the  mind, 
in  the  employment  of  galvanism,  has  any  share 
in  the  relief  obtained  from  it.  I had  not  at  this 
time  seen  its  effects  in  apoplexy.  I found  that 
by  scratching  the  skin  with  the  sharp  end  of  a 
wire  I could  produce  a sensation  so  similar  to  that 
excited  by  galvanism,  that  those  who  had  most 
frequently  been  subjected  to  this  influence  were 
deceived  by  it.  By  this  method,  and  arranging 
the  trough,  pieces  of  metal,  &c.  as  usual,  I de- 
ceived several  who  had  formerly  received  relief 
from  galvanism,  and  also  several  who  had  not  yet 
used  it.  All  of  them  said  that  they  experienced 
no  relief  from  what  I did.  Without  allowing 
them  to  rise,  I substituted  for  this  process  the  real 
application  of  galvanism,  merely  by  immersing  in 
the  trough  one  end  of  the  wire  with  which  I had 
scratched  the  nape  of  the  neck,  the  wire  at  the  pit 
of  the  stomach  having  been  all  the  time  applied 
as  usual  by  the  patients  themselves.  Before  the 


315 


application  of  the  galvanism  had  been  continued 
as  long  as  the  previous  process,  they  all  said  they 
were  relieved.  I relate  the  particulars  of  the  two 
following  experiments,  because  independently  of 
the  principal  object  in  view  in  making  them,  they 
point  ont  two  circumstances  of  importance  in  judg- 
ing of  the  modus  operandi  of  galvanism  in  asth- 
matic cases. 

The  first  was  made  on  an  unusually  intelligent 
lady,  of  about  thirty-five  years  of  age,  who  had 
for  many  years  laboured  under  habitual  asthma, 
than  whom  I have  known  none  more  capable  of 
giving  a distinct  account  of  their  feelings.  Her 
breathiug  was  very  much  oppressed  at  the  time 
that  she  first  used  galvanism.  The  immediate 
effect  was,  that  she  breathed  with  ease.  She  said 
she  had  not  breathed  so  well  for  many  years. 
Part  of  the  relief  she  obtained  proved  permanent, 
and,  when  she  was  galvanised  once  a day  for 
about  ten  minutes,  she  suffered  little  dyspnoea  at 
any  time.  After  she  had  been  galvanised  for  eight 
or  ten  days,  I deceived  her  in  the  manner  just 
mentioned.  The  deception  was  complete.  She 
told  me  to  increase  or  lessen  the  force  of  the  gal- 
vanism, as  she  was  accustomed  to  do,  according 
to  the  sensation  it  produced.  I obeyed  her  di- 
rections by  increasing  or  lessening  the  force  with 
which  I scratched  the  neck  with  the  wire.  After 
I had  done  this  for  five  minutes,  she  said  the  gal- 
vanism did  not  relieve  her  as  usual,  and  that  she 


316 


felt  the  state  of  her  breathing  the  same  as  when 
the  operation  was  begun.  I then  allowed  the  gal- 
vanism to  pass  through  the  chest,  but  only  through 
the  upper  part  of  it,  the  wire  in  front  being  ap- 
plied about  the  middle  of  the  sternum.  She  soon 
said  that  she  felt  a little  relief ; but  although  it 
was  continued  in  this  way  for  ten  minutes,  the  re- 
lief was  imperfect.  I then  directed  her  to  apply 
the  wire  in  front  to  the  pit  of  the  stomach,  so  that 
the  galvanism  passed  through  the  whole  extent  of 
the  chest,  and,  in  a minute  and  a half,  she  said 
her  breathing  was  easy,  and  that  she  now  experi- 
enced the  whole  of  the  effect  of  the  former  appli- 
cations of  the  remedy. 

To  try  how  far  the  effect  of  galvanism  in  asth- 
ma arises  merely  from  its  stimulating  the  spinal 
marrow,  in  a young  woman  who  had  been  seve- 
ral times  galvanised  in  the  usual  way,  the  wires 
were  applied  to  the  nape  of  the  neck  and  small  of 
the  back,  and  thus  the  galvanic  influence  was  sent 
along  the  spine  for  nearly  a quarter  of  an  hour. 
She  said  her  breathing  was  easier,  but  not  so  much 
so  as  on  the  former  applications  of  the  galvanism  ; 
and  on  attempting  to  walk  up  stairs  she  began 
to  pant,  and  found  her  breathing,  when  she  had 
gone  about  half  way,  as  difficult  as  before  the  gal- 
vanism was  applied.  She  was  then  galvanised 
in  the  usual  way  for  five  minutes  : she  now  said 
her  breathing  was  quite  easy,  and  she  walked  up 
the  whole  of  the  stairs  without  bringing  on  any 


317 


degree  of  panting,  or  feeling  any  dyspnoea.  The 
above  experiment  was  made  in  the  presence  of 
four  medical  gentlemen.  This  patient,  after  re- 
maining free  from  her  disease  about  half  a year, 
returned  to  the  Infirmary,  labouring  under  a 
slighter  degree  of  it,  and  experienced  immediate 
relief  from  galvanism.  The  disease  seemed  to 
have  been  renewed  by  cold,  which  had  at  the 
same  time  produced  other  complaints.  This  is 
one  of  the  cases  above  alluded  to  in  speaking  of 
the  permanency  of  the  good  effects  of  galvanism. 
On  the  return  of  this  patient  to  the  Infirmary, 
two  or  three  applications  of  galvanism,  combined 
with  means  which  had  given  no  permanent  relief 
to  the  dyspnoea  previous  to  her  first  using  galvan- 
ism, now  soon  removed  it.  When  she  first  used 
galvanism,  it  required  its  constant  employment 
once  or  twice  a-day  for  several  weeks  to  produce 
the  same  effect.  There  is  reason  to  believe  she 
will  remain  well  if  she  can  avoid  taking  severe 
colds. 

Many  medical  gentlemen  have  frequently  wit- 
nessed the  relief  afforded  by  galvanism  in  habitual 
asthma,  and  Mr.  Cole,  the  house  surgeon  of  the 
Worcester  Infirmary,  authorises  me  to  say,  that 
no  other  means  there  employed  have  been  equally 
efficacious  in  relieving  this  disease. 

Observations  similar  to  the  foregoing,  there 
is  reason  to  believe,  will  be  found  to  apply  to 


318 


dyspepsia,  but  as  I have  made  but  few  trials  of 
galvanisnj  in  this  disease,  except  where  it  was 
complicated  with  asthma,  the  removal  of  which 
no  doubt  contributed  to  a more  healthy  action  of 
the  digestive  organs,  I cannot  yet  speak  with 
certainty  of  its  effects  in  this  disease.  In  some, 
galvanism,  at  the  time  of  its  application,  occasions 
a tendency  to  sighing;  and  in  some,  in  whom  it 
removed  the  dyspnoea,  it  seemed  to  occasion  a 
sense  of  sinking  referred  to  the  pit  of  the  sto- 
mach. This  occurred  in  several  instances,  and 
was  relieved  by  small  doses  of  carbonate  of  iron 
and  bitters. 

That  I may  convey  to  the  reader  as  correct 
an  idea  as  I can  of  the  effects  of  galvanism  in 
habitual  asthma,  I shall  concisely  relate  the  par- 
ticulars of  a few  of  the  most,  and  of  the  least, 
successful  cases,  in  which  it  was  employed. 

Richard  Morgan,  a blacksmith,  set.  50,  had 
laboured  under  severe  habitual  asthma  for  seven 
months,  during  which  he  had  been  better  and 
worse  for  a few  weeks,  but  never  free  from  dysp- 
noea. He  was  much  troubled  with  a cough,  the 
expectorated  matter  being  thick,  and  of  a yellow- 
ish colour.  The  dyspnoea  was  particularly  severe 
at  the  time  he  was  galvanised,  and  had  been  so 
for  about  a fortnight.  The  first  application  of  the 
galvanism  relieved  him.  He  was  galvanised  only 
for  three  days,  about  ten  minutes  each  day,  before 


319 


he  declared  himself  to  be  perfectly  well.  He  re- 
turned to  his  work,  which  he  had  been  obliged  to 
abandon,  after  the  second  application  of  the  gal- 
vanism. After  its  third  application  he  performed 
as  hard  work,  and  with  as  much  ease,  as  he  had 
ever  done. 

He  remained  free  from  dyspnoea  till  it  was  re- 
newed, several  weeks  afterwards,  by  his  getting 
drunk.  Galvanism  relieved  him  as  readily  and 
effectually  as  at  first.  It  is  now  ten  months  since 
he  first  used  this  remedy,  during  which  he  has 
had  several  returns  of  dyspnoea,  but  it  has  never 
been  so  severe  as  before  he  was  galvanised ; and 
when  it  has  been  such  as  to  induce  him  to  have 
recourse  to  galvanism,  he  has  always  experienced 
from  it  immediate  relief.  He  ascribes  the  returns 
of  his  disease  to  his  being  exposed  to  severe  and 
sudden  heats  and  chills. 

Mary  M‘Konchy,  £et.  28,  a gloveress,  had  been 
afflicted  with  habitual  asthma  for  four  years,  and 
under  my  care  about  one  year,  during  which  she 
had  tried  all  the  usual  means  with  very  imper- 
fect relief ; she  had  some  languor  in  the  biliary 
system,  but  little  inflammatory  tendency.  The 
breathing  was,  in  a few  minutes,  rendered  easy 
by  galvanism,  anti  after  the  second  application  of 
it,  it  remained  so.  She  now  experienced  no  in- 
convenience from  exercise,  which  had  not  at  any 
time  been  the  case  for  four  years. 


320 


In  about  three  weeks  after  she  had  been  gal- 
vanised she  experienced  some  return  of  the 
dyspnoea.  It  was  wholly  removed  by  a blister, 
which  had  often  been  tried,  previous  to  her  being 
galvanised,  with  but  little  and  very  temporary 
relief.  She  complained  of  a sense  of  sinking  at 
the  stomach  for  some  time  after  the  use  of  the  gal- 
vanism, which  was  removed  by  carbonate  of  iron 
and  bitters.  This  effect  of  galvanism  seemed 
often  to  be  most  felt  when  it  gave  most  relief  to 
the  dyspnoea,  seeming  to  come  in  place  of  the 
latter.  I have  hitherto  found  it  easily  removed 
by  the  above  means.  It  is  now  many  months 
since  this  patient  was  galvanised,  and  she  re- 
mains well. 

Hannah  Cooke,  set.  20,  a servant,  had  labour- 
ed under  habitual  asthma  for  two  months,  and 
tried  various  medicines  without  relief.  She  was 
in  a few  minutes  relieved  by  galvanism,  and  after 
three  applications  of  it,  remained  quite  well.  It 
is  now  five  or  six  weeks  since  she  was  galvanised. 

I could  mention  several  other  cases,  in  which 
I witnessed  the  same  sudden  and  permanent  re- 
lief from  galvanism,  as  in  those  here  related. 

Isaac  Radley,  set.  68,  a labourer,  formerly  a 
soldier,  had  been  ill  14  years.  His  asthma  was 
caused  by  sleeping  in  camp  in  Holland.  He  had 
never  been  able,  during  the  above  time,  to  walk 


321 


at  the  usual  pace  without  bringing  on  the  dysp- 
noea, although  he  had  sometimes  been  pretty  free 
from  it  when  he  was  still ; at  other  times  he  had 
been  constantly  oppressed  with  it,  and  obliged 
wholly  to  abandon  his  work.  At  the  time  he  used 
the  galvanism,  he  was  affected  with  the  most  se- 
vere dyspnoea,  which  only  allowed  him  to  move, 
and  that  with  difficulty,  at  the  slowest  pace ; he 
had  been  in  this  state  for  half  a year.  This  was 
the  longest  and  most  severe  fit  he  had  ever  had. 
He  was  relieved  in  a few  minutes  by  the  applica- 
tion of  galvanism.  He  could  perceive  its  bene- 
ficial effects  for  twenty-four  hours  after  its  appli- 
cation. It  was  used  daily  with  the  same  imme- 
diate relief.  Its  permanent  good  effects  gradually 
encreased,  and  after  he  had  been  galvanised  for 
about  ten  minutes  each  day,  for  between  two  and 
three  weeks,  his  breathing  remained  quite  easy. 
He  could  now  not  only  walk,  but,  as  I several 
times  witnessed,  run  without  any  dyspnoea.  He 
complained  of  the  sense  of  sinking  at  the  pit  of 
the  stomach  after  the  dyspnoea  had  left  him, 
which,  as  in  the  case  just  mentioned,  was  readily 
removed  by  the  carbonate  of  iron  and  bitters.  He 
now  said  his  digestion  w as  much  better  than  it 
had  been  previously  to  the  use  of  the  galvanism. 
Those  whose  breathing  had  been  much  relieved 
by  galvanism,  often  made  this  observation,  al- 
though they  had  not  experienced  the  sense  of  sink- 

43 


322 

ing,  and  consequently  had  used  no  stomachic  me- 
dicines. 

I saw  this  man,  several  months  after  he  had 
ceased  to  use  galvanism,  working  as  a bricklayer's 
labourer.  He  said  he  had  no  feeling  of  dyspnoea, 
and  had  been  quite  free  from  it  since  he  had  used 
the  galvanism. 

In  general,  where  galvanism  gave  such  com- 
plete and  permanent  relief,  as  in  Radley’s  case, 
its  effects  were  more  speedy,  some  degree  of  dysp- 
noea for  the  most  part  remaining  in  protracted 
cases. 

The  following  are  the  most  unsuccessful  cases, 
which  either  Mr.  Cole  or  I could  recollect. 

Martha  Davies,  a servant,  set.  40,  had  laboured 
under  habitual  asthma  for  five  years.  She  was 
relieved  on  the  first  application  of  galvanism,  and 
said  her  breathing  was  quite  easy ; but  she  was 
not  always  equally  relieved  by  it,  sometimes  it 
gave  comparatively  little  relief.  The  more  per- 
manent relief  afforded,  was  also  different  at  dif- 
ferent times,  never  complete.  She  was  galvan- 
ised for  about  three  weeks,  but  not  daily,  her 
business  preventing  her  regular  attendance  ; she 
used  the  remedy  in  all  about  thirteen  or  fourteen 
times.  It  was  impossible  to  prevent  her  drink- 
ing a great  deal  too  much  malt  liquor. 

It  is  now  about  half  a year  since  she  was  gal- 


323 


vanised,  during  which  she  says  both  her  breath- 
ing and  digestion  have  been  better  than  for  the 
preceding  five  years.  She  thinks  the  digestion 
as  much  improved  as  the  breathing.  She  has  had 
no  very  bad  attacks  of  dyspnoea,  and  has  been 
much  less  subject  to  bilious  attacks.  She  is  now 
occasionally  so  well  that  she  can  run  without  in- 
convenience, which  she  could  never  do  during 
the  above  time,  but,  in  general,  her  breathing, 
though  in  a less  degree  than  formerly,  is  still  op- 
pressed. 

Mary  Clark,  a servant,  set.  24,  had  laboured 
under  habitual  asthma  for  about  a year.  The 
dyspnoea  was  always  quickly  relieved  by  the 
galvanism,  although  she  seemed  to  experience  lit- 
tle, if  any,  permanent  relief  from  it.  She  had 
more  pain  in  the  stomach  than  is  usual  in  such 
cases,  and  the  galvanism  seemed  to  increase  it. 
She  was  cured  by  an  alternative  course  of  medi- 
cines and  evacuations  from  the  region  of  the  sto- 
mach, and  did  not  use  galvanism  for  the  last  fort- 
night. She  had  used  it  at  first  daily  for  a fort- 
night, and  twice  afterwards  for  a week  each  time. 

As  far  as  I can  judge  from  having  observed  the 
course  of  many  cases  of  this  kind,  her  recovery 
would  neither  have  been  so  speedy  nor  complete 
if  she  had  not  used  galvanism. 

Rachel  Hooper,  set.  29,  a servant,  had  laboured 


324 


under  severe  habitual  asthma  for  about  a year, 
with  considerable  inflammatory  tendency.  Her 
breathing  was  relieved  in  a few  minutes  by  gal- 
vanism, but  not  completely.  For  about  eight  or 
ten  days,  during  which  she  was  galvanised  daily 
for  about  ten  minutes,  she  derived  from  it  con- 
siderable relief,  both  immediate  and  permanent. 
It  then  began  to  fail  to  give  relief,  and  in  a few 
days  gave  none.  The  epigastric  region  was  now 
very  tender  on  pressure.  This  symptom  was 
relieved  in  the  space  of  a few  days  by  local  blood- 
letting, blistering  and  small  doses  of  calomel. 
The  relief  afforded  by  the  galvanism  was  now 
greater  than  at  first,  which  seemed  to  arise  from 
the  disease  not  being  so  severe  as  on  the  first  use 
of  the  remedy,  for  some  part  of  the  good  effects 
of  the  galvanism  had  remained.  After  this  she 
was  always  relieved  by  it  as  long  as  she  conti- 
nued to  use  it,  which  was  for  several  weeks.  The 
permanent  relief  she  experienced  from  it  was 
also  great,  although  she  still  at  times  laboured 
under  a considerable  degree  of  dyspnoea.  About 
half  a year  ago,  she  left  Worcester  with  a pro- 
mise to  return,  if  she  should  get  worse.  I have 
heard  nothing  of  her  since. 

She  said  nothing  else  had  given  her  so  much, 
either  immediate  or  permanent  relief,  as  the  gal- 
vanism had  done.  She  had  been  for  several 
months  in  the  Infirmary  under  other  plans  of 
treatment  before  she  used  the  galvanism.  All 


B25 


the  patients  whose  cases  I have  mentioned  were 
galvanised  at  the  Infirmary. 

The  following  is  a remarkable  instance  of  per- 
manent,  though  imperfect  relief,  from  galvanism, 
in  the  disease  before  us.  A woman,  who  had  for 
many  years  laboured  under  severe  habitual  asth- 
ma, was  incautiously  galvanised  with  such  a 
power  as  occasioned  severe  pain.  No  entreaty 
could  induce  her  to  submit  to  a repetition  of  the 
galvanism,  although  it  had  immediately  relieved 
her  breathing.  The  dyspnoea  soon  recurred,  but 
she  told  me  many  months  afterwards  that  it  had 
never  been  so  severe  since  she  was  galvanised, 
and  that  she  had  ever  since  been  able  to  carry 
water  in  buckets  from  the  river,  which  the  state 
of  her  breathing  had  not  for  a long  time  pre- 
viously allowed  her  to  do. 

If  the  reader  will  compare  these  cases  with  the 
general  observations  which  I have  had  occasion 
to  make  on  the  etfects  of  galvanism  in  habitual 
asthma,  he  will  be  enabled  to  form  a pretty  cor- 
rect estimate  of  what  he  may  expect  from  its  em- 
ployment in  this  disease. 

When  we  compare  them  with  the  experiments 
laid  before  the  reader  in  the  preceding  Inquiry, 
the  question  naturally  arises,  whence  proceeds  the 
permanent  relief  obtained  in  them  ? The  galvanic 
experiments  lead  us  to  expect  relief  to  the  dysp- 


326 


noea  while  the  stream  of  galvanism  passes  through 
the  lungs  ; but  on  what  principle  shall  we  explain 
the  permanency  of  the  relief  afforded?  The  fol- 
lowing observations  appear  to  throw  some  light 
on  this  subject.  There  are  two  ways  in  which 
an  organ  may  be  deprived  of  its  nervous  influence, 
either  by  a failure  of  due  action  in  the  brain  and 
spinal  marrow,  the  sources  of  nervous  influence, 
or  a failure  of  due  action  in  the  nerves  of  the  or- 
gan affected,  by  which  this  influence  is  conveyed. 
It  is  no  longer  conveyed  by  a nerve  which  has 
been  divided,  or  around  which  a ligature  has  been 
thrown.  Now  we  have  reason  to  believe  that  ha- 
bitual asthma  arises  not  so  much  from  a fault  in 
the  brain  and  spinal  marrow,  as  in  the  nerves  of 
the  lungs ; because,  did  the  degree  of  dyspnoea, 
which  we  often  witness  in  this  disease,  arise  from 
failure  in  the  general  source  of  nervous  influence, 
this  failure  must  be  sufficient  to  appear  in  the  de- 
rangement of  all  the  nervous  functions ; whereas 
in  habitual  asthma,  we  often  find  the  function  of 
the  lungs  alone  affected ; and  when  general  fail- 
ure of  nervous  influence  is  observed,  it  is  evidently 
the  effect  of  impeded  respiration,  appearing  only 
after  the  latter  has  continued  for  some  time,  and 
varying  as  it  varies.  The  effect  produced  by  gal- 
vanism, when  it  performs  a cure  in  habitual  asth- 
ma, therefore,  does  not  appear  to  be  its  having 
occasioned  a permanent  supply  of  nervous  in- 
fluence, but  its  having  cleared,  if  I may  use  the 


expression,  the  passage  of  this  influence  to  the 
lungs.  It  is  not  difficult  to  conceive  that  such  an 
obstruction  may  exist  in  the  nerves  as  cannot  be 
overcome  by  the  usual  supply  of  nervous  influence, 
though  it  may  yield  to  a greatly  increased  supply 
of  it ; and  that  it  may  in  some  cases  continually 
recur  in  an  equal  or  diminished  degree,  while  in 
others,  being  once  removed,  the  tendency  to  it 
may  cease.* 

The  foregoing  observations  seem  to  explain 
why  other  means,  which  give  a temporary  vi- 
gour to  the  nervous  system,  often,  for  the  time, 
relieve  habitual  asthma  ; and  sometimes,  though 
rarely,  cure  this  disease.  The  relief  obtained 
from  such  means  being  in  general  so  much  less 
than  that  obtained  from  galvanism,  I would  as- 
cribe to  the  former  occasioning  but  little  addition- 
al supply  of  nervous  influence,  while  by  the  latter 
we  can  make  the  additional  supply  as  great  as  we 
please. 

* What  is  here  said  is  well  illustrated  by  the  effects  of  gal- 
vanism in  apoplexy.  We  know  that  in  this  disease  the  dysp- 
noea arises  from  a failure  in  the  source  of  nervous  influence, 
and  the  relief  obtained  from  galvanism  corresponds  with  the 
views  afforded  by  the  experiments  which  have  been  laid  be- 
fore the  reader.  While  the  galvanism  passed  through  the 
lungs  the  dyspnoea  was  as  much  relieved  as  in  habitual  asth- 
ma, but  when  it  ceased  to  pass  through  them,  the  relief  lasted 
no  longer  than  was  necessary  for  the  re-accumulation  of  the 
phlegm. 


328 


Of  Suspended  Animation. 

The  last  disease  which  I shall  mention  is  sus- 
pended animation  from  drowning,  or  other  causes 
obstructing  the  breathing.  Inflating  the  lungs 
seems  here  to  act  in  two  ways.  It  gives  to  the 
blood  of  the  smaller  vessels  of  the  lungs  the  arte- 
rial properties  by  which  they  are  excited  to  ac- 
tion ; and  acting  through  the  blood  of  these  ves- 
sels, it  communicates  to  that  of  the  larger  vessels, 
and  of  the  heart  itself,  more  or  less  of  the  same 
properties,  independently  of  the  blood  already 
changed  being  moved  on  towards  this  organ ; for 
M.  le  Gallois  has  shewn,  that  after  the  circula- 
tion has  permanently  ceased,  the  blood  may  be 
changed,  by  inflating  the  lungs,  not  only  in  the 
heart  itself,  but  also  in  some  part  of  the  larger 
arteries.  By  these  means  the  circulation  in  the 
lungs  is  restored,  but  it  is  evident  from  the  expe- 
riments which  have  been  laid  before  the  reader, 
that  their  due  action  cannot  be  restored  till  they 
receive  their  usual  supply  of  nervous  influence. 
Now  this  cannot  happen  till  the  re-established 
circulation  has  renewed  the  vigour  of  the  brain 
and  spinal  marrow.  We  have  reason  to  believe, 
that  could  the  due  degree  of  this  influence  be  re- 
stored to  the  lungs  as  soou  as  the  circulation  is 
renewed  in  them  by  the  access  of  the  air,  they 


329 


would  be  excited  to  a more  perfect  performance 
of  their  functions ; and  that  recovery  might  thus 
be  effected  in  some  cases,  where  inflation  of  the 
lungs  alone  would  fail. 

We  have  seen,  from  direct  experiment,  that 
galvanism  can  supply  the  place  of  nervous  influ- 
ence in  the  lungs,  enabling  them  to  perform  their 
functions  after  the  latter  is  withdrawn.  I would 
therefore  propose,  that,  to  the  means  employed 
for  the  recovery  of  suffocated  persons,  an  appara- 
tus, properly  adapted  for  sending  a stream  of  gal- 
vanism through  the  lungs  in  the  direction  of  their 
nerves,  as  above  pointed  out,  should  be  added.  It 
would  be  improper  here  to  employ,  for  any  con- 
siderable length  of  time,  a stronger  power  than 
experience  has  taught  us  can  be  used  without  bad 
effects  in  health.  The  power  should  not  exceed 
that  of  fifteen,  or  at  most,  twenty-four  inch  double 
plates  of  zinc  and  copper,  the  fluid  being  one  part 
of  muriatic  acid  and  twenty  of  water. 

I should  expect  little  advantage  from  galvan- 
ism applied  to  any  other  secreting  organ,  because 
the  revival  of  the  patient  depends  little,  if  at  all, 
on  the  action  of  any  other.  Employed  as  a ge- 
neral stimulus  to  the  brain  and  spinal  marrow,  it 
may  be  of  use  by  rousing  the  dormant  powers  of 
the  system.  They  are  all,  we  have  seen,  capa- 
ble of  being  excited  through  these  organs.  In 
this  way  it  can  only  indirectly  assist  the  lungs, 

44 


330 


and  that  chiefly  in  proportion  to  the  degree  in 
which  general  circulation  is  restored.  It  is  pro- 
bable, that,  as  a general  stimulus,  a greater  power 
of  galvanism  may  be  used  without  injury,  than  it 
would  be  proper  to  send  through  any  vital  organ 
for  a considerable  length  of  time,  because,  em- 
ployed with  this  view,  it  may  be  applied  inter- 
ruptedly. 

Of  Sympathy. 

Do  not  the  experiments  which  have  been  laid 
before  the  reader  tend  to  throw  some  light  on 
the  nature  of  the  sympathy  which  exists  between 
different  parts  of  the  body,  and  so  extensively 
influences  the  symptoms  and  treatment  of  dis- 
eases?* If  it  appears  that  the  nervous  influence 
is  not  only  capable  of  exciting,  and  acting  as  a 
sedative  to,  the  moving  fibre  wherever  it  exists, 
and  whether  subject  to  the  will  or  not.f  and  of 
influencing  in  every  possible  way  the  secreting 
process, % but  is  itself  of  such  a nature,  that  it  is 
capable  of  pervading  equally  the  solids  and  fluids 

* I have,  in  a paper  above  referred  to,  published  in  the 
seventh  volume  of  tlte  Medico-Chirurgical  Transactions, 
enumerated  some  of  the  more  striking  instances  in  which 
the  sympathy  of  parts  influences  the  symptoms  and  treat- 
ment of  diseases. 

t Part  II.  Chap.  2.  f Chap.  5,  Sec.  1 and  5. 


331 


of  the  body,  and  of  being  instantly  moved  from 
place  to  place  independently  of  any  immediate 
connection  of  vessels  or  nerves,*  it  will  not  be 
difficult  to  explain  the  various  phenomena  of 
sympathy,  many  of  which,  at  first  view,  appear 
so  unaccountable. 

* Chap.  5,  Sec.  2.  The  phenomena  of  sympathy  seem 
always  to  take  place  through  the  intervention  of  the  brain 
or  spinal  marrow. 


V,  :r.<,iXy  . ) ... 

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APPENDIX. 


The  following  account  of  an  experiment  which, 
I am  informed,  is  supposed  by  many  to  contra- 
dict the  result  of  the  galvanic  experiments  which 
have  been  laid  before  the  reader,*  was  sent  to 
me. 

11  Two  rabbits,  which  had  had  no  food  for  se- 
venteen hours,  were  allowed  to  eat  parsley.  The 
nerves  of  the  were  then  divided  in  the 

neck  of  each.  One  of  them  was  allowed  to  re- 
main quiet.  A slip  of  tin  foil  was  connected  to 
the  lower  divided  ends  of  the  nerves  of  the  other 
rabbit,  and  another  piece  of  tin  foil,  an  inch 
square,  was  applied  to  the  abdominal  muscles 
over  the  stomach,  and  under  the  integuments,  by 
means  of  a wound  in  the  latter.  The  tin  foil  over 
the  stomach  was  connected  with  a wire  communi- 
cating with  one  end  of  a voltaic  battery  of  twenty 
plates,  and  occasional  contacts  were  made,  (about 
three  or  four  times  a minute,)  between  a wire  con- 
nected with  the  other  end  of  the  battery  and  the 
tin  foil  in  the  neck.  The  influence  of  the  battery 
was  sufficiently  strong  to  excite  slight  contrac- 
tions of  the  muscles  of  the  fore-legs.  This  pro- 


* Exp.  46,  47,  48,  49. 


334 


cess  was  continued  during  five  hours,  at  the  end 
of  which  period  both  rabbits  were  killed. 

“On  examining  the  stomach  of  the  animal, 
which  had  been  subjected  to  the  influence  of  the 
battery,  it  was  found  much  distended  with  food  ; 
the  parsley  was  principally  in  the  cardiac  portion, 
and  near  the  oesophagus  it  appeared  to  have  un- 
dergone no  alteration  ; and  below  this  it  was 
mixed  with  the  other  food  in  the  stomach,  so  that 
no  accurate  observation  could  be  made  on  it. 

“ The  stomach  of  the  other  rabbit  was  exa- 
mined by  the  side  of  the  first,  so  that  they  might 
be  compared  together,  and  the  appearances  were 
precisely  the  same  with  those  which  have  been 
just  described.  The  contraction  in  the  centre  of 
the  stomach  was  somewhat  greater  in  the  galvan- 
ised stomach  than  in  the  other.” 

It  is  perhaps  unnecessary  to  observe  that  this 
experiment,  except  in  the  most  unimportant  cir- 
cumstances, bears  no  resemblance  to  any  of  the 
galvanic  experiments  related  in  the  preceding  In- 
quiry. In  the  above  account  of  it,  which  is 
printed  in  the  way  it  was  sent  to  me,  it  is  not 
stated  what  nerves  were  divided,  and  no  symp- 
tom is  mentioned  which  can  lead  us  to  suppose 
that  they  were  the  nerves  of  the  eighth  pair ; 
while  the  appearances  after  death  demonstrate 
that  these  nerves  had  not  been  divided,  the  state 
of  the  contents  of  the  stomachs  of  both  rabbits  be- 
ing such  as  it  is  never  found  to  be,  when  they 


335 


have  been  divided  some  hours  previous  to  death.* 
Had  the  proper  nerves  been  divided,  the  experi- 
ment would  still  have  been  inconclusive,  as  far 
as  relates  to  my  experiments,  because  no  con- 
tinued stream  of  galvanism  was  sent  through  the 
stomach,  but  only  “occasional  contacts”  of  the 
metals  were  made.  It  is  unnecessary  to  point  out 
some  minor  circumstances,  in  which  the  above 
experiment  dilfers  from  the  galvanic  experiments 
in  question.  In  repeating  such  experiments,  it 
is  evident,  every  circumstance  should  be  carefully 
considered.  Even  trivial  differences  in  the  mode 
of  making  them  often  occasion  essential  differences 
in  the  result. 

* Page  161  et.  seq 


THE  END. 


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